i 


573    Sb7 


GIFT   OF 


«^      1S%^ 


Manual 

of 

General  Agriculture 


EDWARD  P.   TERRY 


Manual  of 
General  Agriculture 


BY 

EDWARD  P.  TERRY,  M.  S. 

Assistant  Supervisor  of  Agriculture  in  the 
Los  Angeles  City  Schools 


LOS  ANGELES,  CALIFORNIA 


COPYRIGHT,   1912  BY 
EDWARD  P.  TERRY 


TIMES-MIRROR   PTG.  &   BDG.  HOUSE.  LOS  ANGELES.  CAU 


INTRODUCTION 

The  experiments  in  this  manual  represent  actual 
work  done  by  the  author's  classes  during  several  years 
teaching  of  the  subject  of  general  agriculture  in  High 
Schools  in  Northern  and  Southern  California.  There  is 
sufficient  material  to  occupy  the  laboratory  time  of  a 
High  School  class  at  least  four  periods  a  week  for  one 
year.  Not  all  the  exercises  are  suitable  for  any  one 
locality,  but  nearly  all  can  be  used  any  place.  The 
manual  is  not  intended  to  displace  any  text. 

A  satisfactory  plan  for  conducting  a  course  in  gen- 
eral agriculture  is  to  have  each  student  own  a  manual  and 
have  the  school  furnish  the  references  to  accompany  it. 
As  the  recitations  do  not  occur  every  day,  one  book  for 
three  students  will  be  found  sufficient.  Usually  the  local 
library  will  supply  a  portion  of  the  books  needed.  A  list 
of  references  will  be  found  in  the  back  of  this  manual. 

A  note  book  containing  a  record  of  each  exercise  per- 
formed should  be  kept  by  the  student.  The  following 
form  is  suggested: 

Number  and  statement  of  exercise. 

Exercise. 

Result. 

Conclusion. 

It  is  unnecessary  for  the  student  to  copy  materials. 
At  the  beginning  of  nearly  all  the  exercises  will  be  found 
a  list  of  materials  needed,  but  special  attention  is  called 
to  the  following,  the  materials  for  which  cannot  be  ob- 
tained at  once :  46,  56,  57,  58,  59,  62,  63,  64,  67,  68,  69. 

The  author  wishes  to  express  his  thanks  for  council 
and  material  contributed  by  Principal  E.  L.  Mitchel,  Pro- 
fessors W.  T.  Clarke,  R.  H.  Loughridge,  A.  D.  MacGil- 
livray,  H.  H.  Whetzel,  C.  S.  Wilson,  E.  G.  Montgomery, 
Messrs.  A.  R.  Tyler,  Geo.  C.  Roeding  and  Miss  May  Kimble. 
The  cuts  under  Budding  and  Grafting  were  taken  from 
Farmers'  Bulletin  No.  157.  With  slight  changes,  exer- 
cises 31,  32,  33,  34,  45,  46,  47  and  50  are  by  Prof.  F.  E. 
Edwards. 

310256 


CONTENTS 


PART  I.     PHYSICAL  PROPERTIES  OF  SOILS. 

Page 

1.  How  Soils  are  Formed 7 

2.  Taking  Soil  Samples 7 

3.  Microscopical  Examination  of  Soil  Particles....  8 

4.  Determination  of  Total  Moisture  in  the  Soil ...  9 

5.  Capillarity 10 

6.  Effect  of  Drainage  on  Soil  Temperature 11 

7.  Effect  of  Color  on  Soil  Temperature 12 

8.  Effect  of  Evaporation  on  Soil  Temperature 13 

9.  Per  Cent,  of  Air  in  Soils 14 

10.  Separation  of  Sand,  Silt  and  Clay  in  Soils 14 

11.  Water  Holding  Capacity  of  Soils 15 

12.  Effect  of  Humus  on  Water  Holding  Capacity  of 

Soils  16 

13.  Effect  of  Mulches  and  Cultivation  on  Evapora- 

tion from  the  Soil 16 

14.  Effect  of  Vegetable  Matter  on  the  Capillary  Rise 

of  Water 17 

15.  Effect  of  a  Moist  Atmosphere  on  Dry  Soils....  17 

16.  Effect  of  Lime  on  Soils 18 

17.  One  Effect  of  Humus,  of  Sand  and  of  Lime,  on  a 

Clay  Soil 19 

18.  Determination  of  the  Specific  Gravity  of  Soils. .  19 

19.  Determination  of  the  Apparent  Specific  Gravity 

of  Soils 20 

PART  II.     CHEMICAL  PROPERTIES  OF  SOILS. 
SOIL  ANALYSIS. 

20.  Acids,  Alkalis  and  Salts 21 

21.  Preparation  of  Potash 22 

22.  Preparation  of  Crude  Phosphoric  Acid "...  22 

23.  Alkali  Soils   23 

24.  Gypsum  Treatment  for  Black  Alkali 25 

25.  Acid  Soils  and  How  to  Correct  Them 25 

26.  Directions  for  Obtaining  Soil  Samples 27 


CONTENTS.  5 

Page. 

27.  Determination  of  Nitrogen    28 

28.  Determination  of  Phosphoric  Acid 29 

29.  Determination  of  Lime 30 

30.  Determination  of  Alkali 31 

PART  III.  CHEMISTRY  OF  PLANTS. 

31.  Moisture  in  the  Plant 33 

32.  Composition  of  Dry  Matter  of  Plants 33 

33.  Composition  of  Plant   Ash 34 

34.  ^  Nitrogen  in  Plants 36 

35.  >  Plant  Nutrition 36 

36.  Nitrogen  in  Nodules. 39 

37.  Tests  for  Principal  Classes  of  Plant  Compounds . .  40 

38.  Occurrence  and  Extracting  of  Starch 41 

39.  Inversion  of  Cane  Sugar 42 

40.  Preparation  of  Glucose 42 

41.  Essential  Oil  From  Plants 43 

42.  Extraction  of  Proteids 43 

43.  Extraction  and  Decomposition  of  Chlorophyll. .  44 

44.  Determination  of  Oil  in  Flaxseed 44 

45.  Absorption  of  Manure  by  the  Soil 45 

46.  Fertilizer  Field  Tests 45 

PART  IV.  AGRICULTURAL  BOTANY  AND  PLANT 
PROPAGATION. 

47.  Conditions  Necessary  for  Germination. 47 

48.  Purity  of  Seed  and  Germination  Test 47 

49.  Plump  and  Shrunken  Seeds 49 

50.  Depth   of  Germination 49 

51.  Osmosis   50 

52.  The  Work  of  Leaves 51 

53.  Study  of  the  Characters  of  Barley 52 

54.  Outline  for  Describing  Grasses 58 

55.  Identification  of  Clover  and  Grass  Seeds 59 

56.  Cuttings  and  Their  Use  in  Propagation 60 

57.  Establishing  a  Deciduous  Orchard 62 

58.  Grafting 65 

59.  Budding    69 


6  CONTENTS. 

Page 

60.  Laying  out  an  Orchard 72 

61.  How  to  Plant  a  Tree 73 

62.  Propagation  of  the  Grape   74 

63.  Propagation  of  the  Orange  77 

64.  Pruning  Fruit  Trees,  Vines  and  Bushes 78 

65.  Structure  and  Nature  of  Fungi    81 

66.  Structure  and  Nature  of  Bacteria    81 

PART  V.    ENEMIES  OF  CROPS. 

67.  Apple  Scab 83 

68.  Fire  Blight  or  Pear  Blight 85 

69.  The  Mouth-parts  of  Insects 88 

PART  VI.     TESTING  MILK  AND  ITS  PRODUCTS. 

70.  Experiments  With  Milk 94 

71.  Analysis  of  Milk 95 

72.  Test  for  Mineral  Salts  in  the  Ash  of  Milk 97 

73.  Calibration  or  Correction  of  Glassware 98 

74.  Determination  of  the  Specific  Gravity  or  Strength 

of  Sulphuric  Acid 99 

75.  The  Babcock  Test  of  Milk    100 

76.  The  Babcock  Test  of  Cream    103 

77.  The  Babcock  Test  of  Skim  Milk 104 

78.  The  Lactometer  and  Its  Application. 105 

79.  Testing   the   Acidity   or    Sourness   of   Milk   and 

Cream    107 

80.  Calculation  of  the  Percentage  of  Milk  Solids 107 

81.  Test  for  Physical  Adulteration  of  Milk 108 

82.  Test  for  Chemical  Adulteration  of  Milk 109 

83.  Determination  of  Moisture  in  Butter 110 

84.  Determination  of  Salt  in  Butter 112 

85.  Determination  of  Per  Cent.  Fat  in  Ice-cream. .  .112 

86.  Standardization  of  Milk  and  of  Cream..  .113 


MANUAL  OF  GENERAL  AGRICULTURE.  7 

PART  I.     PHYSICAL  PROPERTIES  OF  SOILS. 

1.  HOW  SOILS  ARE  FORMED.     (FIELD  EXERCISE.) 

(a)  Work  of  Atmosphere. — 1.    Note  any  rocks  worn 
away  by  the  friction  of  wind  or  sand  through  the  action 
of  the  wind.     Note  any  rocks  kept  exposed  to  other  at- 
mospheric agencies  through  the  action  of  the  wind;  note 
any  wind-blown  soil;  any  wind-blown  water. 

2.  Note  any  evidences  of  chemical  action;  oxida- 
tion; action  of  carbon  dioxid;  ''rotten  rock."  Make  a 
drawing  showing  successive  stages  of  disintegration  from 
solid  rock  to  soil. 

(b)  Work  of  Water. — 1.    Note  any  evidences  of  its 
solvent  power.    Fill  a  small  bottle  with  clear  water  from 
a  spring  or  brook  and  when  you  return  to  the  laboratory 
evaporate  a  few  drops  of  it  on  a  piece  of  glass  or  in  a  test 
tube,  and  see  if  there  is  any  residue ;  explain. 

2.  Disintegrating  Power  of  Water. — Note  evidences 
of  the   washing   out   of  loose   material,   and   of  cutting 
power  of  the  water;  of  the  abrasion  caused  by  gravel, 
pebbles  and  stones. 

3.  Transporting    Power    of    Water. — Why    is    one 
stream  clear,  and  another  muddy?     Note   any  sand  or 
soil  dropped  by  water. 

4.  Note    evidences    of    assorting    power    of    water. 
Draw  a  section  of  the  bank  of  a  stream,  showing  stratifi- 
cation. 

5.  Note  evidences  of  under-ground  streams,  of  land- 
slides, and  describe  and  explain. 

2.  TAKING  SOIL  SAMPLES.     (FIELD  EXERCISE.) 

Materials:  Spade,  pai$  two  one  quart  fruit  jars, 
or  two  bottles  with  corks. 

Select  a  spot  for  sampling  and  remove  any  leaves 
and  twigs  from  the  surface.  Dig  into  the  cleared  space 
a  V-shaped  hole,  with  one  side  of  the  V  perpendicular. 
On  the  perpendicular  side  measure  the  depth  to  the 
change  in  color,  which  indicates  the  division  between  sur- 
face soil  and  subsoil.  With  the  spade  shave  thin  slices 
from  the  perpendicular  side  to  the  depth  of  the  surface 


8  MANUAL  OF  GENERAL  AGEICULTUEE. 

soil,  collecting  the  soil  in  a  pail  until  you  have  about  a 
quart.  If  there  is  no  marked  line  between  soil  and  sub- 
soil, sample  to  a  depth  of  one  foot. 

Without  filling  up  the  hole  go  to  at  least  one  other 
part  of  the  field  and  in  a  similar  manner  obtain  another 
sample,  place  in  the  pail  with  the  first  sample  and  mix 
thoroughly.  Save  about  a  quart  as  a  sample  of  the  field, 
and  keep  air-tight  to  prevent  loss  by  evaporation. 

Continue  digging  to  the  depth  of  about  one  foot  be- 
low the  surface  soil  and  collect  a  sample  of  subsoil  by 
shaving  thin  slices  as  before  and  placing  in  the  pail.  Fill 
up  the  hole.  Return  to  the  original  hole  and  obtain  a 
sample  of  subsoil,  mix  the  two  subsoils  and  keep  air-tight 
as  was  done  with  the  surface  soil. 

3.    MICROSCOPICAL  EXAMINATION  OF  SOIL 
PARTICLES. 

Materials :  Compound  microscope,  sand,  loam  or  silt, 
clay  soil,  or  clay. 

Place  a  few  grains  of  sand  on  a  glass  slide  and  ex- 
amine with  low  power  of  a  microscope. 

Make  drawings  of  several  of  the  particles  and  de- 
scribe them  with  reference  to  color;  shape  (angular, 
rounded,  or  irregular) ;  simple  or  compound  (joined  to- 
gether) •  coarse,  medium  or  fine. 

Mix  loam  or  silt  with  a  little  water  and  examine  a 
drop,  using  medium  power.  Draw  and  describe  as  above. 

Mix  clay  soil  with  water  and  examine  a  drop  of  the 
slightly  muddy  water  using  the  high  power.  Notice  that 
the  soil  particles  are  really  minute  rocks  and  humus. 
Find  dark  particles  of  humus.  Find  flocculated  particles 
of  clay,  i.e.  a  number  of  particles  united  to  form  a  com- 
pound particle.  Draw  and  describe.  Keeping  a  clay  soil 
in  good  condition  is  largely  a  matter  of  keeping  the  par- 
ticles thus  flocculated  or  united  into  small  crumbs. 


MANUAL  OF  GENERAL  AGRICULTURE. 


4.     DETERMINATION  OF  TOTAL  MOISTURE  IN 
THE  SOIL. 

Materials:  Four  tin  pans,  sheet  iron  drying  oven*, 
samples  collected  in  Exercise  2. 

Number,  mark  with  your  initials  and  accurately 
weigh  four  pans.  Record  weights  in  your  note  book. 
Run  all  your  experiments  in  duplicate  for  the  sake  of 
greater  accuracy. 

Place  in  pans  1  and  2,  50  grams  of  surface  soil,  and 
in  pans  3  and  4,  50  grams  of  subsoil.  Put  them  in  the  dry- 
ing oven  for  at  least  five  hours  at  a  temperature  of  100 
to  110  degrees  centigrade.  Cool  to  room  temperature 
and  weigh  at  once.  The  loss  in  weight  represents  the 
total  moisture  content  of  the  soil. 

Tabulate  the  results  as  follows: 

TOTAL  MOISTURE  IN  SOILS. 


Kind  of 
Soil 

Pan 
No. 

Wt.  of 

Pan 

Wt.  of 
Soil 

Wt.  of 

Dry  Soil 

Loss  of 
Weight 

Per  Cent 
Moisture 

1 

50g. 

2 

Avg. 

Kind  of 
Soil 

3 

4 

Avg. 

Questions:  1.  What  were  the  weather  conditions 
at  the  time  of  taking  the  samples?  2.  Approximately, 
when  was  the  last  heavy  rain?  3.  Does  the  soil  or  sub- 
soil have  the  most  moisture?  "Why? 

*A  better  oven  is  of  copper  set  on  a  strong  iron  frame.  It 
should  be  about  10  in.  high,  10  in.  deep,  and  12  in.  wide.  The 
oven  is  provided  with  a  centigrade  thermometer  and  has  a  vent 
for  the  escape  of  moisture.  It  costs  approximately  eight  dollars. 
As  it  is  needed  throughout  the  entire  course,  it  is  advisable  to 
obtain  one. 


10  MANUAL  OF  GENERAL  AGRICULTURE. 

5.    CAPILLARITY. 

Materials:  Glass  tubes  having  internal  diameters 
ranging  from  one-sixteenth  to  one  inch,  4  pans,  evaporat- 
ing dish,  alcohol  or  kerosene.  Soil  and  subsoil  collected 
in  Exercise  2.  For  (d),  4  glass  tubes  at  least  4  ft.  long 
and  of  any  diameter  up  to  one  inch,  the  larger  the 
better,  pan,  sand,  sandy  soil,  loam,  clay,  small  cloth  and 
string. 

(a)  Place  the  ends  of  the  tubes  side  by  side  in  a 
pan  of  water.     Describe  what  takes. place  in  the  tubes. 
1.    Does  the  water  rise  on  the  inside  of  each  tube  or  does 
it  rise  on  both  the  inside  and  outside?    2.     If  two  tubes 
are  placed  side  by  side  and  as  close  together  as  possible, 
what  effect  has  this  on  the  rise  of  water  between  them? 

(b)  Into  a  small  wide  mouth  bottle  or  evaporating 
dish,  pour  alcohol  or  kerosene  until  it  stands  about  ^in. 
deep.     Fill  the  bottle  with  dry  sand  or  finely  divided 
air-dry  soil  and  press  down  firmly.     Let  stand  for  about 
15  minutes,  then  apply  a  lighted  match.    Result?    What 
does  this  show?     This  experiment  represents  accurately 
the  capillary  rise  of  water  in  soils  to  replace  that  used  by 
the  plant  or  that  lost  by  evaporation. 

(c)  Number  and  weigh  four  pans,  and  place  in  each 
of  two  50  grams  of  soil,  and  in  each  of  the  remaining 
two  50  grams  of  subsoil.     With  a  pestle  or   glass  rod 
break  up  all  lumps,  at  the  same  time  spreading  the  soil 
evenly  on  the  bottom  of  the  pans.     Set  aside  and  leave 
undisturbed   until   the   next   laboratory   period.      Weigh 
again  and  continue  to  weigh  at  each  successive  period 
until  the  weights  become   constant.     Compute  the   per- 
centage of  capillary  moisture  on  the  basis  of  water  free 
soil  as  found  in  Exercise  4.    The.  difference  between  the 
total    moisture    and    the    amount    of    capillary    moisture 
represents  the   hygroscopic  moisture   of  soil.     Calculate 
the  per  cent  hygroscopic  moisture  in  the  samples  under 
consideration. 

(d)  Close  one  end  of  each  tube  using  a  piece  of 
cloth  and  tying  with  a  string.    Fill  the  tubes  with  finely 


MANUAL  OF  GENEEAL  AGEICULTUEE.  11 

divided  air-dry  sand,  sandy  loam,  loam  and  clay.  Do  not 
separate  the  coarse  and  fine  particles.  Compact  the  soil 
by  letting  the  tubes  drop  onto  a  book,  taking  care  to 
let  the  tubes  drop  the  same  number  of  times  and  the  same 
distance.  Support  the  tubes  so  that  the  ends  dip  about 
one  inch  in  water  in  the  bottom  of  a  pan.  Observe  the 
height  to  which  the  water  has  risen  at  the  end  of  1  hr., 
2  hr.,  4  Mr.,  6  hr.,  at  the  next  meeting  of  the  class,  and 
at  each  meeting  thereafter  for  two  weeks  or  more.  Keep 
a  paper  by  each  tube  showing  1,  the  height  of  the  mois- 
ture, 2,  time  and  day  of  each  reading.  Record  results 
in  tabular  form  in  your  note-book. 

Questions:  1.  Which  tube  shows  the  most  rapid 
rise  ?  2.  At  the  end  of  an  hour,  which  shows  the  greatest 
rise?  3.  At  the  end  of  a  week?  4.  What  effect  does 
size  of  particles  have  on  rapidity  of  movement  ? 

6.    EFFECT  OF  DRAINAGE  ON  SOIL  TEMPERATURE. 

Materials :  Five-gallon  oil  can  with  one  side  removed, 
wooden  box  approximately  the  same  dimensions. 

Fill  each  with  the  same  kind  of  soil  and  apply  the 
same  amount  of  water  until  drainage  begins  in  the  box. 
There  will  be  no  drainage  from  the  can.  If  necessary, 
loosen  a  board  in  the  bottom  of  the  box.  Let  the  two 
stand  out  of  doors  until  the  following  day.  Begin  as  early 
in  the  morning  as  possible  and  take  the  temperatures 
hourly  at  depths  of  1  and  3  inches  until  5  P.M.  Record 
results  on  a  piece  of  paper  left  by  the  vessels. 

Let  some  pupil  who  lives  near  wet  land  record  the 
temperatures  of  this  land  together  with  the  temperature 
of  adjacent  dry  land  at  convenient  intervals  some  Satur- 
day. Compare  his  temperatures  with  those  of  the  experi- 
ment. Tabulate  the  results.  Give  explanations  for  dif- 
ferences in  temperatures. 

Question:  If  drainage  effects  the  temperature,  how 
may  it  affect  a  crop? 


12 


MANUAL  OF  GENEEAL  AGRICULTUEE. 


7.     EFFECT  OF  COLOR  ON  SOIL  TEMPERATURE. 

Materials:  Two  cigar  boxes,  soot,  slaked  lime,  two 
thermometers,  seeds. 

Place  well  pulverized  moist  soil  into  two  cigar  boxes, 
filling  them  about  half  full.  In  one-half  of  one  box,  bury 
twelve  seeds  1/2  inch  deep,  using  bean,  corn,  wheat,  or  any 
other  quick  germinating  seeds  which  may  be  on  hand.  In 
the  other  half  plant  12  seeds  of  some  other  plant.  Cover 
both  plantings  with  chalk  dust,  slaked  lime  or  white  ashes 
to  a  depth  of  %  inch. 

In  the  same  manner  plant  the  same  number  and  the 
same  kinds  of  seeds  in  the  other  box,  but  instead  of  using 
light  colored  covering,  use  soot. 

Each  time  the  class  meets  after  the  second  day  ob- 
serve the  number  of  plants  showing  above  the  surface, 
keeping  a  record  of  the  dates  and  kinds  sprouted  on  the 
side  of  the  box.  In  the  morning  of  a  clear  day  insert  a 
thermometer  into  each  box  to  about  the  depth  of  the 
sprouted  seeds.  After  a  few  minutes,  when  the  thermom- 
eters have  become  adjusted  to  the  new  temperatures,  take 
the  readings.  Continue  to  take  the  readings  hourly 
throughout  the  day.  Record  the  results  as  follows: 


DAYS  TO  SPROUT 


TEMPERATURE 


Light  Soil 
Beans     Peas 


Dark  Soil 


Time 


Beans 


Peas 


8A.M. 
9A.M. 

10  A.M. 

11  A.M. 

12  M. 
1P.M. 
2P.M. 
3P.M. 
4P.M. 
5P.M. 


Light    I    Dark 
Soil  Soil 


Question : 
Why? 


Which  soil  shows  the  higher  temperature  ? 


MANUAL  OF  GENERAL  AGRICULTURE. 


13 


8.     EFFECT  OF  EVAPORATION  ON  SOIL  TEMPERA- 
TURE. 

Materials:  Two  tomato  cans,  2  thermometers,  plot- 
ting paper. 

Fill  two  tomato  cans  with  air-dry  soil  and  saturate 
one  with  water.  Bury  the  cans  side  by  side  in  a  sunny 
spot,  leaving  about  %  inch  of  the  tops  above  the  surface. 
Insert  a  thermometer  into  each  to  a  depth  of  about  1  inch. 
The  following  day  as  early  as  possible  take  the  first  read- 
ing and  continue  taking  readings  every  hour  thereafter 
until  5  P.M.  On  plotting  paper  draw  a  curve  of  tempera- 
ture for  each  can,  using  TIME  and  TEMPERATURE  for 
the  co-ordinates  as  shown  in  the  diagram. 


88 


8 


10 


TIME 
11       12 


H 


fifi 

fi° 

60 

58 

56 

51 

52 

RO 

18 

46 

14 

42 

40 

14  MANUAL  OF  GENEEAL  AGEICULTUEE. 

How  to  plot  the  curve.  Suppose  at  8  o'clock  it  was 
found  that  the  temperature  of  the  saturated  soil  was  61 
degrees  F.,  a  dot  should  be  placed  half  way  between  60 
degrees  and  62  degrees  on  the  8  o'clock  line ;  if  at  9  o'clock 
the  temperature  was  61.5  degrees,  the  second  dot  should 
be  placed  *4  of  a  division  higher  on  the  9  o'clock  line. 
Continue  to  put  dots  for  all  your  temperatures.  Connect 
the  dots  by  a  straight  or  broken  line. 

9.     PER  CENT  OF  AIR  IN  SOILS. 

Materials:  Three  beakers  or  bottles,  graduate,  sand, 
clay,  and  loam. 

Put  25  cc.  of  sand  in  one  beaker,  25  cc.  of  clay  in  the 
second,  and  25  cc.  of  loam  in  the  third.  Fill  the  graduate 
to  the  50  cc.  mark  with  water  and  pour  on  to  each  sample 
until  the  water  just  rises  to  the  surface.  The  amount  of 
water  required  is  an  approximate  measure  of  the  air  space, 
since  the  water  displaces  the  air.  Figure  out  the  per  cent 
of  air  space  in  each  sample. 

Question:  What  effect  does  size  of  particles  have  on 
total  amount  of  air  space  ? 

10.     SEPARATION   OF  SAND,   SILT  AND   CLAY  IN 

SOILS. 

Materials:  Tall  beaker  of  about  500  cc.  capacity, 
flask  with  long  narrow  neck,  mortar,  rubber  pestle  made 
by  inserting  a  glass  rod  into  a  one-hole  stopper. 

Weigh  out  exactly  20  grams  of  air-dry  soil  and  place 
it  in  a  mortar ;  add  12  cc.  water  and  rub  with  the  pestle. 
Let  it  settle  a  minute  and  pour  off  the  muddy  water  into 
the  tall  beaker.  Add  more  water  to  the  mortar  and  repeat 
until  the  water  in  the  mortar  no  longer  gets  muddy.  The 
part  remaining  is  coarse  sand. 

With  small  amounts  of  water  wash  the  sand  from  the 
mortar  through  a  funnel  into  a  long  necked  flask. 

Add  water  to  the  beaker  containing  muddy  water 
until  it  is  nearly  filled.  Stir  and  let  stand  for  an  hour,  or 


MANUAL  OF  GENEBAL  AGEICULTUEE.  15 

until  the  next  meeting.  The  muddy  appearance  of  the 
water  is  due  to  the  clay,  which  remains  in  suspension. 
Siphon  off  without  disturbing  the  sediment  and  keep  both 
the  siphoned  portion  and  the  residue.  Fill  the  beaker 
again  with  water,  stir,  let  settle  an  hour  and  siphon  as 
before.  Repeat  until  after  standing  an  hour  the  water 
above  the  sediment  is  clear.  Add  the  siphoned  portion  to 
that  obtained  before.  Transfer  the  sediment  to  the  flask 
containing  the  sand.  Nearly  fill  with  water  and  stopper 
well.  Shake  and  invert  on  a  ring-stand  so  that  the  neck 
is  perpendicular.  After  the  small  particles  have  settled, 
note  the  different  layers  of  sand  at  the  bottom,  to  fine  silt. 
Ascertain  approximately  by  volume  the  percentages  of 
sand,  silt  and  clay. 

11.    WATER  HOLDING  CAPACITY  OP  SOILS. 

Materials:  Air-dry  sand,  clay,  loam,  three  student 
lamp  chimneys,  cheesecloth,  string. 

Tie  a  piece  of  cheesecloth  over  the  bottom  of  a  chim- 
ney, moisten  the  cloth  and  weigh  accurately.  Fill  the 
chimney  with  dry  sand  and  compact  by  dropping  onto  a 
book  a  counted  number  of  times  from  the  same  height. 
Weigh  it  again  and  stand  it  in  a  trough  containing  sev- 
eral inches  of  water.  Leave  it  in  this  position  until  the 
surface  of  the  sand  becomes  thoroughly  moist.  Remove 
the  tube,  wipe  dry,  and  weigh  again.  Cover  the  tube  with 
cotton  and  set  it  where  the  water  will  drain  away.  "Weigh 
later  in  the  day  and  at  each  meeting  of  the  class  there- 
after for  at  least  5  days.  In  the  same  way  prepare  tubes 
using  clay  and  loam  or  any  other  soil. 

If  the  soil  used  is  very  dry  there  should  be  no  capil- 
lary moisture,  but  the  hygroscopic  moisture  is  still  in  the 
samples,  hence  the  results  will  be  too  low.  For  more 
accurate  results  the  hygroscopic  moisture  should  be  deter- 
mined. Express  your  results  in  tabular  form. 

Questions:  1.  Which  soil  loses  water  more  rapidly? 
2.  Which  takes  the  longest  time  to  percolate? 


16  MANUAL  OF  GENERAL  AGRICULTURE. 

12.  EFFECT  OF  HUMUS  ON  WATER  HOLDING 
CAPACITY  OF  SOILS. 

Materials:     Three  tin  cans,  dry  well-rotted  manure. 

Perforate  the  bottoms  of  three  tin  cans.  Place  a  piece 
of  cheesecloth  on  the  bottom  of  each  and  weigh,  recording 
the  weights  on  the  outside  of  each.  Place  in  one  95  grams 
of  sand,  and  5  grams  of  well-rotted  manure ;  into  another 
85  grams  of  sand  and  15  grams  well-rotted  manure;  into 
the  third  75  grams  sand  and  25  grams  well-rotted  manure. 
Saturate  each  with  water  and  weigh  immediately.  Write 
results  in  each  case  as  follows: 

Sand  containing  5%  organic  matter  retained  — % 
moisture,  etc. 

13.     EFFECT  OF  MULCHES  AND  CULTIVATION  ON 
EVAPORATION  FROM  THE  SOIL. 

Materials:     As  indicated  in  exercise. 

Secure  three  five-gallon  oil  cans  and  cut  them  in  half 
with  a  can  opener.  In  case  the  upper  half  of  any  one  can- 
not be  made  water-tight  another  must  be  used.  Place  an 
inch  of  gravel  in  each.  Place  in  the  corner  of  each  a  stu- 
dent lamp  chimney. 

Fill  each  can  with  soil  to  within  two  inches  of  the 
top,  slightly  compacting  the  soil.  Number  the  cans  from 
one  to  six.  Cover  the  soil  in  number  five  with  one  inch  of 
sand.  Cover  number  six  with  one  inch  of  stable  manure. 

Weigh  each  can  and  record  its  weight.  Bury  the 
cans  in  an  open  place  until  the  surfaces  inside  and  out  are 
on  the  same  level.  Place  them  in  a  row  according  to  num- 
bers and  about  two  feet  apart.  Pour  into  each  chimney 
a  measured  amount  of  water,  allowing  time  for  the  soil  to 
absorb  it.  When  the  cans  without  a  mulch  show  damp- 
ness on  top  discontinue.  Continue  the  experiment  as  fol- 
lows: 

No.  1,  check,  let  alone. 

No.  2,  cultivate  one  inch  deep  once  a  week. 

No.  3,  cultivate  two  inches  deep  once  a  week. 

No.  4,  cultivate  three  inches  deep  once  a  week. 

No.  5,  let  alone.        No.  6,  let  alone. 


MANUAL  OF  GENEEAL  AGEICULTUEE.  17 

Continue  the  experiment  at  least  six  weeks,  adding 
measured  quantities  of  water  to  the  cans  as  they  need  it 
to  keep  the  surfaces  in  good  condition  for  crop  growth. 
At  the  end  of  the  required  time  dig  up  the  cans,  wipe  the 
outsides  clean  and  weigh.  Add  to  the  original  weight  of 
each  can  of  soil,  the  weight  of  the  water  added,  and  sub- 
tract from  the  result  the  last  weight  of  the  can.  The  dif- 
ference represents  the  amount  of  water  evaporated.  Tab- 
ulate the  results. 

Questions:  How  may  a  farmer  obtain  an  artificial 
mulch  ?  A  natural  mulch  ? 

14.  EFFECT  OF  VEGETABLE  MATTER  ON  THE  CAP- 

ILLARY RISE  OF  WATER. 

Materials:  Air-dry  soil,  sawdust,  well  rotted  ma- 
nure, tubes  as  indicated  in  experiment. 

Obtain  three  glass  tubes  about  an  inch  in  diameter 
and  two  feet  long.  Close  the  ends  of  each  by  means  of 
cheesecloth  firmly  tied  on.  Fill  one  tube  with  well  pulver- 
ized air-dry  soil  and  compact  slightly.  Into  a  second  tube 
place  the  same  kind  of  soil  to  the  depth  of  one-half  its 
length,  and  then  place  a  two-inch  layer  of  sawdust,  and 
finally  fill  to  the  top  with  soil  and  compact  as  above.  In 
the  third  tube  use  finely  divided  well-rotted  manure  in 
place  of  sawdust.  Place  the  tubes  so  that  the  lower  ends 
stand  about  an  inch  deep  in  water.  At  the  next  labora- 
tory period  notice  the  rise  of  capillary  water.  Leave  for 
another  laboratory  period,  at  which  time  write  up  the  ex- 
periment and  put  away  the  apparatus.  Assuming  that  the 
crop  roots  go  below  the  straw  or  manure  plowed  under, 
state  the  effect  of  plowing  under  a  large  amount  of  straw 
or  poorly  rotted  manure. 

15.  EFFECT  OF  A  MOIST  ATMOSPHERE  ON  DRY 

SOILS. 

Materials:  Sand,  clay,  loam,  3  fruit  jars,  3  small 
receptacles  to  hold  water  and  small  enough  to  go  into  the 
jars,  scales. 

Place  100  grams  of  air-dry  sand  in  an  accurately 
weighed  fruit  jar.  Place  in  the  jar  a  small  receptacle  con- 


18  MANUAL  OF  GENEBAL  AGKRICULTUBE. 

taining  water.  Tightly  close  the  fruit  jar  and  set  in  the 
sun.  Repeat,  using  clay  and  loam.  "Weigh  at  each  labora- 
tory meeting  thereafter  until  the  weight  becomes  constant. 
Remove  the  receptacle  at  each  weighing. 

Calculate  the  amount  of  moisture  absorbed  in  each 
case.  These  amounts  are  not  the  total  moisture  since  the 
hygroscopic  moisture  was  always  present. 

Questions:  1.  Which  class  of  soils  absorb  the  larg- 
est amount  of  moisture,  and  why?  2.  If  soil  absorbs  so 
little  moisture  from  a  saturated  atmosphere;  why  do 
wilted  plants  "freshen"  on  a  foggy  morning? 

16.     EFFECT  OF  LIME  ON  SOILS. 

Materials:  Clay  or  clay  soil,  2  cigar  boxes,  slaked 
lime. 

Prepare  four  moulds  one  inch  in  width  and  the  length 
of  the  width  of  the  cigar  box.  Use  pieces  of  one  cigar  box 
for  the  partitions  in  the  other,  thus  having  the  four 
moulds  in  one  box.  "Weigh  out  four  100  gr.  samples  of 
clay  soil  and  add  the  following  amounts  of  well-pulverized 
slaked  lime : 

No.  1,  add  none. 

No.  2,  add  one  gram. 

No.  3,  add  five  grams. 

No.  4,  add  ten  grams. 

Mix  each  sample  thoroughly  in  a  pan,  then  add  just 
enough  water  to  make  the  soil  plastic.  Mould  each  sam- 
ple into  a  form  of  a  stick  by  compressing  the  moist  clay  in 
the  moulds.  Leave  in  the  sun  at  least  a  week,  or  bake  in 
an  oven  until  thoroughly  dry.  Remove  the  sticks  and 
determine  the  weight  necessary  to  break  each  in  the  fol- 
lowing manner: 

Rest  the  ends  of  a  stick  of  clay  upon  supports  and  sus- 
pend from  its  center  a  bucket  into  which  sand  is  slowly 
poured. 

Tabulate  the  results. 

Questions:  1.  How  does  lime  effect  the  tenacity  of 
clay?  2.  What  effect  on  the  physical  condition  of  clay 
has  lime? 


MANUAL  OF  GENERAL  AGRICULTURE.  19 

17.  ONE  EFFECT  OF    HUMUS,  OF    SAND,  AND  OF 

LIME,  ON  A  CLAY  SOIL. 

Materials:     Four  pans,  clay,  slaked  lime,  sand. 

Fill  four  pans  i/4  full  of  clay  and  treat  as  follows : 

To  the  first  add  enough  water  to  saturate  the  clay. 
Make  a  note  of  the  amount  of  water  used. 

To  the  second  add  about  l/2  its  volume  of  humus  or 
fine,  dry,  well-rotted  manure,  and  the  same  amount  of 
water  as  before. 

To  the  third  add  *4  its  volume  of  slaked  lime  and 
water,  the  same  as  before. 

To  the  fourth  add  %  its  volume  of  sand  and  the  same 
amount  of  water  as  before.  Make  each  into  a  ball  and  set 
aside  to  dry.  In  a  few  days  examine  and  see  which  one 
can  be  more  easily  pulverized  with  the  fingers. 

Questions:  1.  State  the  conclusions  as  to  the  value 
of  humus,  sand,  and  lime  on  a  clay  soil  as  shown  in  this 
experiment.  2.  What  causes  a  clay  soil  to  bake.  3. 
How  can  the  baking  of  a  clay  soil  be  prevented  ? 

18.  DETERMINATION  OF  THE  SPECIFIC  GRAVITY 

OF  SOILS. 

Materials:  Graduated  cylinder  (25  cc.  or  50  cc.), 
sand,  clay  and  loam  soils. 

In  this  experiment  we  are  to  compare  the  weights  of 
different  soils  with  the  weights  of  equal  volumes  of  water. 
Ascertain  the  weight  of  10  cc.  of  water.  Place  exactly 
10  cc.  of  water  in  the  cylinder,  reading  to  the  top  of  the 
column  but  not  including  the  crescent  formed  on  the  sur- 
face of  the  column.  This  water  crescent  is  called  the  '  *  men- 
iscus." Pour  10  grams  of  accurately-weighed  sand  which 
has  been  dried  to  a  constant  weight  into  the  water.  Shake 
to  expel  the  air.  Take  the  reading  as  before,  not  includ- 
ing the  meniscus.  Subtract  10  from  this  reading,  and  the 
remainder  is  the  volume  of  water  displaced  by  the  sand. 
Determine  the  weight  of  displaced  water  and  calculate  the 
specific  gravity  according  to  the  following  formula: 

Wt  S. 
Sp.=  - 

wt.  w. 


20  MANUAL  OF  GENERAL  AGRICULTURE. 

in  which  Sp.=specific  gravity,  Wt.  S.=weight  of  sand  or 
soil,  and  Wt.  W.=weight  of  water  displaced.  Calculate 
the  specific  gravity  of  clay  and  loan  soils.* 

Questions:  1.  What  is  specific  gravity?  2.  Why 
is  it  necessary  to  use  water-free  soils?  3.  How  does  the 
amount  of  humus  affect  the  specific  gravity? 

The  specific  gravity  of  the  material  which  forms  the 
great  bulk  of  most  soils  is  about  2.6.  But  the  soil  is  not  a 
solid  mass.  It  is  composed  of  spherical  particles  which 
touch  each  other  at  different  points.  About  50%  of  a  cul- 
tivated soil  is  air-space.  Hence  this  air  space  reduces  the 
weight  of  a  volume  of  soil  much  below  the  specific  grav- 
ity of  its  constituents.  In  this  experiment  we  really  found 
the  specific  gravity  of  the  constituents,  which  is  termed 
"real  specific  gravity."  In  the  following  experiment  we 
are  to  determine  the  specific  gravity,  including  air-space, 
which  is  termed  "apparent  specific  gravity." 

19.     DETERMINATION     OF    APPARENT    SPECIFIC 
GRAVITY  OF  SOILS. 

Materials:     Same  as  in  last  experiment. 
In  this  experiment  we  are  to  determine  the  ratio  of 
unit  weight  to  unit  volume  of  different  soils. 

Pour  into  a  dry  cylinder  10  cc.  water-free  sand. 
Weigh  the  sand.  Having  already  determined  the  weight 
of  10  cc.  water  calculate  the  apparent  specific  gravity 
according  to  the  following  formula : 

V.  S. 
Sp.= 

y.  wt.  w. 

Wt.  S.=weight  of  soil  (i.e.,  weight  of  10  cc.  soil),  V.  Wt. 
W.=weight  of  water  (i.  e.,  weight  of  10  cc.  water). 

Questions:  1.  What  influence  have  stones  upon  the 
apparent  specific  gravity?  2.  What  influence  has  plow- 

*In  general  when  cubic  centimeters  and  grams  are  used  the 
specific  gravity  of  a  body  is  found  by  the  formula: 

Wt.  body. 
Sp.  Gr.  of  Body=  — 

Vol.  body. 


MANUAL  OF  GENEEAL  AGRICULTURE.  21 

ing  upon  apparent  specific  gravity?  3.  The  apparent 
specific  gravity  of  soils  in  the  field  may  be  taken  as  an 
indication  of  the  tilth  of  soils.  Why? 

PART  II— CHEMICAL  PROPERTIES  OF  SOILS. 
SOIL  ANALYSIS. 

If  you  have  taFen  or  are  now  taking  chemistry  pro- 
ceed at  once  with  Exercise  20.  If  you  have  not  studied 
chemistry,  obtain  some  chemistry  manual  and  perform  the 
following  experiments,  as  therein  described: 

(1)  Preparation  of  Oxygen. 

(2)  Preparation  of  Hydrogen. 

(3)  Preparation  of  Carbon  dioxid. 

(4)  Preparation  of  Nitrogen. 

The  teacher  should  give  a  demonstration  on  labora- 
tory manipulation  to  students  unfamiliar  with  chemistry. 
See  any  chemistry  manual. 

20.     ACIDS,  ALKALIS,  AND  SALTS. 

Materials:  Sulphuric  acid,  nitric  acid,  vinegar,  red 
and  blue  litmus  paper,  any  fruit  at  hand,  sodium  and  pot- 
assium hydroxid,  hydrochloric  acid,  evaporating  dish. 

(a)  Illustration  and    test    for    acids:     Add  a  few 
drops  of  sulphuric  acid  to  half  a  tumbler  of  water.    Add 
drop  by  drop,  tasting  each  time  until  the  flavor  can  be 
distinguished.    Do  the  same  with  nitric  acid. 

Compare  the  taste  of  each  with  that  of  vinegar.  Put 
red  and  blue  litmus  paper  into  the  three  substances  used 
above.  Result?  This  is  a  sure  test  for  acids.  Test  the 
juice  of  any  fruit  at  hand.  Result? 

(b)  Illustrations  and  test    for    alkalis.     Dissolve  a 
small  piece  of  sodium  hydroxid  (caustic  soda)  and  another 
small  piece  of  potassium  hydroxid  (caustic  potash),  each 
in  about  20  cc.  of  water.     How  does  each  solution  feel? 
Test  with  both  kinds  of  litmus  paper.    Result? 

Dip  your  finger  into  each  solution  and  cautiously 
taste.  This  bitter  taste,  soapy  feeling,  and  alkalin  reac- 
tion, are  the  most  characteristic  properties  of  alkalis. 


22  MANUAL  OF  GENERAL  AGRICULTURE. 

(c)  Illustration  and  test  for  a  salt.  Pour  out  10  cc. 
of  hydrochloric  acid  into  an  evaporating  dish  and  add  an 
equal  volume  (10  cc.)  of  water.  Add  sodium  hydroxid 
made  in  (b)  until  the  solution  is  neutralized;  i.  e.,  until 
neither  shade  of  litmus  is  changed  in  the  solution.  Evap- 
orate to  dryness  by  heating.  Watch  the  evaporating 
toward  the  end  and  if  spattering  is  too  vigorous  remove 
the  flame  a  moment.  When  evaporation  is  complete  re- 
move the  salt  and  add  a  little  water. 

Note  the  taste  and  action  on  litmus.  This  is  a  com- 
mon table  salt  (sodium  chlorid). 

Questions:  1.  Name  three  classes  of  chemical  sub- 
stances and  in  tabular  form  give  their  characteristic  prop- 
erties as  indicated  in  this  experiment.  2.  What  is  meant 
by  a  neutral  substance? 

21.     PREPARATION  OF  POTASH. 

Materials:     Wood  ashes,  pan,  evaporating  dish. 

Potash  is  easily  prepared  from  wood  ashes.  Place 
wood  ashes  into  a  pan,  filling  it  about  one-third  full.  Pour 
in  water  until  the  pan  is  about  two-thirds  full  and  stir 
vigorously  for  about  two  minutes,  in  order  to  dissolve  the 
potash  in  the  ashes.  When  the  ashes  have  settled  pour 
off  the  clear  liquid  and  test  with  litmus  paper.  Result? 
Potash  is  one  of  the  alkalis,  which  always  have  this  effect 
upon  litmus.  Notice  the  soapy  feel  and  the  bitter  taste. 

22.  PREPARATION  OF  CRUDE  PHOSPHORIC  ACID. 

Materials:  Bones,  mortar  and  pestle,  red  and  blue 
litmus  paper,  sulphuric  acid,  stirring  rod,  beaker,  filter 
and  filter  paper,  nitric  acid,  test  tube,  ammonium  molyb- 
date.* 

Obtain  some  bones  of  any  kind  and  burn  them  until 
white.  This  white  substance  is  for  the  most  part  a  com- 
bination of  phosphoric  acid  and  lime.  To  remove  the 
lime,  take  about  10  gr.  of  burned  bone  and  pulverize  in  a 
mortar,  transfer  to  a  beaker,  add  50  cc.  of  water  and  5  cc. 
of  sulphuric  acid  and  stir  with  a  stirring  rod  a  few  min- 

*For   the   preparation   of    ammonium    molybdate    see    page    28. 


MANUAL  OF  GENEEAL  AGRICULTURE.  23 

utes.  The  lime  will  combine  with"the  sulphuric  acid  and 
leave  the  phosphoric  acid  in  solution.  By  merely  testing 
the  solution  with  litmus  paper  does  not  prove  the  presence 
of  phosphoric  acid,  even  if  the  blue  does  turn  red,  since 
we  have  added  sulphuric  acid  and  some  of  this  may  not 
have  been  removed  by  combining  with  the  lime.  Hence 
we  must  use  a  special  test  for  phosphoric  acid.  Filter  and 
to  %  of  a  test  tube  of  the  filtered  liquid  (nitrate)  add  3 
or  4  c.c.  of  nitric  acid  and  heat  until  it  just  begins  to  boil. 
Add  !/4  test  tube  of  ammonium  molybdate.  A  yellowish 
color  proves  the  presence  of  phosphoric  acid. 

As  a  control  repeat  the  experiment,  using  10  grams 
of  sand  instead  of  10  grams  of  bone.  Upon  the  addition 
of  ammonium  molybdate  does  the  yellowish  color  appear? 

23.     ALKALI  SOILS. 

Materials:  Three  tomato  cans,  small  pan,  3  evapo- 
rating dishes,  sodium  carbonate,  sodium  chlorid,  sodium 
sulphate,  hydrochloric  acid. 

Among  the  injurious  constituents  of  many  soils  of 
arid  regions  are  certain  salts  collectively  known  as  "al- 
kali. ' '  Whenever  the  rainfall  is  scant  they  are  not  leached 
out  of  the  soil  as  fast  as  formed  and  so  accumulate.  As 
the  rain  water  evaporates  they  are  left  on  the  surface, 
where  they  form  a  white  deposit  known  as  "white  alka- 
li." However,  there  is  also  a  black  alkali  formed  by 
another  salt,  sodium  carbonate.  This  is  the  worst  form  of 
all  since  it  combines  with  the  humus  or  organic  matter  of 
the  soil  to  form  a  black  mass,  and  also  corrodes  the  plant 
just  at  the  surface  of  the  soil  and  kills  it.  Glauber's  salt 
or  sodium  sulphate,  together  with  common  salt  or  sodium 
chlorid,  and  some  others,  form  white  alkali  which  is  much 
less  injurious  than  "black  alkali." 

Obtain  enough  soil  to  fill  the  cans  and  divide  it  into 
three  parts.  Put  one  part  into  a  can  untreated.  Put  an- 
other part  into  the  pan.  Add  15  grams  of  powdered  sodium 
carbonate  and  mix  thoroughly,  then  transfer  to  another 
can.  To  the  last  part  add  5  grams  each  of  sodium  chlorid  and 


24  MANUAL  OF  GENEBAL  AGBICULTUBE. 

sodium  sulphate,  mix  thoroughly  and  place  in  the  third  can. 
Saturate  each,  including  the  first  and  compact  the  surface 
of  the  soil.  Place  the  cans  in  a  warm  place  for  a  week. 
The  first  can  serves  as  a  check.  At  the  end  of  the  week 
what  is  the  difference  in  the  appearance  of  the  surface  of 
the  soil  in  the  three  cans?  Sodium  carbonate  though 
white,  acted  chemically  with  the  humus  in  the  soil  and 
formed  the  black  substance  which,  as  the  water  evapo- 
rated, was  left  on  the  surface,  hence  the  name  "black 
alkali."  The  chemicals  in  the  third  can  did  not  act  chem- 
ically, hence  came  to  the  surface  forming  the  "white  al- 
kali." 

Again  thoroughly  wet  the  soils,  adding  only  a  little 
water  at  a  time  so  that  the  alkali  may  be  washed  down 
into  the  soil  as  it  dissolves.  Beginning  as  soon  as  the  soils 
are  in  condition  to  work,  cultivate  the  cans  to  the  depth 
of  an  inch  every  day  for  a  week.  Why  does  the  alkali  not 
come  to  the  surface  again? 

Perforate  the  bottoms  of  the  cans  with  a  nail.  Place 
each  in  a  separate  pan  and  add  water  a  little  at  a  time 
until  about  a  pint  of  dram  water  is  collected  from  each 
can.  Again  pack  the  soil  surface  and  place  the  cans  in  a 
warm  place  for  two  or  three  days.  Miter  about  100  c.c. 
portions  of  each  of  the  drainage  waters  into  separate  evap- 
orating dishes  and  evaporate  to  dryness.  Is  there  as  much 
residue  in  the  first  sample  as  there  is  in  the  second  and 
third?  With  a  stirring  rod  taste  the  first  residue.  Add 
a  few  drops  of  dilute  hydrochloric  acid  to  the  second  resi- 
due. An  effervescence  (frothing)  shows  carbonates  pres- 
ent. Try  the  first  residue  in  the  same  way.  Is  the  result 
the  same?  Taste  the  third  residue.  Is  it  salty?  Does  it 
taste  like  the  first?  Have  the  alkalis  been  washed  from 
the  soil  ?  After  the  cans  have  stood  for  two  or  three  days 
examine  their  surfaces..  Do  they  show  alkali  as  before? 
Draw  conclusions  from  this  exercise  as  to  the  nature  of 
alkali  and  methods  of  ridding  the  land  of  it. 


MANUAL  OF  GENEEAL  AGRICULTURE.  25 

*<r 

24.     GYPSUM  TREATMENT  FOR  BLACK  ALKALI. 

Materials :    A  tomato  can,  gypsum,  sodium  carbonate. 

Prepare  a  can  of  the  same  kind  of  soil  as  in  the  last 
experiment.  Weigh  out  15  grams  each  of  sodium  carbonate 
and  gypsum  (land  plaster),  powder  each  thoroughly  and 
mix  them  with  the  soil  before  placing  it  in  the  can,  add  wa- 
ter to  the  soil  slowly  until  it  is  saturated.  Compact  as  in 
the  last  experiment.  Place  in  a  warm  place  for  two  days 
and  note  the  incrustation.  Is  it  "black  alkali,"  or  has  the 
gypsum  changed  it?  How  does  the  residue  compare  with 
that  in  the  third  can  in  the  last  experiment?  If  the  ma- 
terials have  been  well  mixed  the  sodium  carbonate  will 
have .  acted  with  the  calcium  sulphate  ( gypsum )  and  formed 
insoluble  calcium  carbonate  (limestone)  and  sodium  sul- 
phate one  of  the  compounds  in  "white  alkali."  In  this 
manner  the  very  harmful  "black  alkali"  can  be  changed 
to  much  less  dangerous  white  variety. 

Besides  containing  harmful  minerals,  most  alkali  soils 
are  rich  in  soluble  plant  food  such  as  nitrates  and  potas- 
sium compounds. 

25.     ACID  SOILS  AND  HOW  TO  CORRECT  THEM. 

An  acid  soil,  litmus  paper,  evaporating  dish,  wood 
ashes  or  slaked  lime,  pan. 

Not  only  do  we  have  alkali  soil,  but  to  a  limited  ex- 
tent in  the  West  we  have  soils  that  are  acid.  They  are 
usually  spoken  of  as  sour  soils.  Some  plants,  notably 
clover  and  alfalfa,  will  not  thrive  in  such  soils  because 
the  soil  bacteria  are  hindered  by  the  acid  present. 

Obtain  some  such  soil  or  soils  from  tule  land,  poorly 
drained  clay  soil,  and  soil  from  the  school  yard  and  test 
as  follows :  Boil  a  sample  a  few  minutes  in  a  small  quan- 
tity of  distilled  water  and  allow  the  soil  to  settle. 

Place  in  the  dish  both  kinds  of  litmus  paper.  Leave 
the  paper  for  several  minutes  as  the  soil  may  be  nearly 
neutral,  i.  e.,  neither  acid  or  alkalin.  Examine  the  lit- 
mus and  compare  each  with  the  original  paper. 

Stir  into  a  soil  known  to  be  alkalin  a  small  handful 
of  slaked  lime  or  wood  ashes  and  test  with  litmus  paper 


26  MANUAL  OF  GENEEAL  AGRICULTURE. 

to  determine  when  enough  has  been  used  to  make  it  neu- 
tral. Use  distilled  water.  What  might  be  applied  to  an 
acid  soil  ?  As  in  the  case  of  alkali,  draining  is  an  effectual 
remedy. 

SOIL  ANALYSIS. 

There  are  in  the  earth's  crust  about  eighty  simple 
substances  called  elements.  Of  these  only  ten  are  neces- 
sary for  plant  growth. 

They  are  nitrogen,  phosphorus,  potassium,  calcium, 
iron,  surphur,  magnesium,  carbon,  oxygen  and  hydrogen. 
In  addition  to  these,  sodium,  silicon,  chlorin  and  alumi- 
num are  -found  in  many  plants,  but  are  not  essential  to 
plant  growth.  None  of  the  above  elements  are  found  in 
the  plant  or  in  the  soil  in  the  elemental  form,  but  are 
always  in  combination  with  other  elements  to  form  com- 
pounds. 

Carbon  is  derived  from  the  carbon  dioxid  of  the  air ; 
hydrogen  and  oxygen  from  the  water  taken  up  by 
plants,  and  the  others  from  the  soil.  Of  the  soil  elements 
potassium,  phosphorus  and  nitrogen,  and  sometimes  cal- 
cium, are  used  by  plants  to  a  much  greater  extent  than 
the  others.  In  fact,  if  the  soil  is  well  supplied  with  these 
four,  so  far  as  plant  food  is  concerned,  it  may  be  consid- 
ered a  rich  soil.  For  this  reason  in  a  short  analysis  of  soils 
the  amounts  of  other  elements  are  never  considered. 

The  manner  in  which  these  four  most  important  ele- 
ments exist  in  the  soil  is:  nitrogen  as  humus  (vegetable 
mould),  phosphorus  in  phosphoric  acid,  potassium  in  pot- 
ash as  in  leached  wood  ashes  which  by  the  removal  of  im- 
purities furnish  potassium  carbonate,  and  calcium  as  lime. 

The  soil-humus  is  the  chief  depository  of  soil  nitrogen 
and  the  main  source  from  which  plants  receive  their  sup- 
ply. True,  the  air  about  us  is  composed  of  four-fifths 
nitrogen,  but  abundant  evidence  shows  that  plants  cannot 
draw  from  this  bountiful  supply.  For  the  most  part, 
humus  is  derived  from  decayed  vegetable  matter,  and  as 
there  is  not  a  rank  vegetation  in  the  arid  regions,  it  fol- 
lows that  the  humus  content  is  one  of  prime  importance 


MANUAL  OF  GENEEAL  AGEICULTUEE.  27 

^r 

in  many  parts  of  California  and  the  West.  The  most  vital 
factor  in  California  agriculture  today  is  the  maintenance 
of  humus.  This  may  be  accomplished  by  crop  rotation 
including  in  the  rotation  a  legume  (pea,  bean,  clover,  al- 
falfa, etc.,)  which  has  the  ability  to  obtain  its  supply  of 
nitrogen  from  the  air  through  the  bacteria  which  this 
order  of  plants  harbors  in  its  roots.  Humus  may  be  di- 
rectly added  to  the  soil  in  the  form  of  manures  and  in 
green  crops  plowed  under.  It  is  customary  to  estimate 
approximately  the  nitrogen  content  of  soils  by  the  propor- 
tion of  humus  present. 

26.     DIRECTIONS  FOR  OBTAINING  SOIL  SAMPLES. 

Materials:  Spade  or  post-hole  augur,  sack  or  board 
or  oilcloth,  quart  jar. 

From  a  representative  part  of  the  field  from  which  soil 
is  to  be  analyzed,  remove  the  leaves  and  twigs  from  the 
surface  and  dig  with  the  spade  or  bore  with  the  post-hole 
augur,  down  to  the  depth  of  four  feet.  Put  all  spade  or 
augurs-ful  of  soil  on  a  clean  sack  or  board.  Mix  all  the  soil 
thus  taken  out,  thoroughly  on  the  sack  or  board,  and  keep 
about  a  quart  of  this  mixed  soil,  which  will  represent  an 
average  of  four  feet  in  the  field. 

To  obtain  a  more  representative  sample,  several  sam- 
ples may  be  taken  in  the  same  way  from  different  places 
and  then  a  quart  from  all  of  them  saved. 

PREPARATION  OF  REAGENTS  FOR  SOIL  ANALYSIS. 

(The  following  should  be  prepared  by  the  teacher  or  some 
trusted  pupil  and  are  enough  for  an  entire  class.) 

Ten  per  cent  solution  of  caustic  potash.  Dissolve  20 
grams  of  solid  caustic  potash  (potassium  hydroxid)  in  200 
c.c.  of  water. 

Dilute  hydrochloric  acid.  Dilute  two  quarts  of  the 
commercial  acid  by  pouring  the  acid  into  eight  quarts  of 
water. 

One-half  per  cent  solution  of  phosphoric  acid.    Dis- 


28  MANUAL  OF  GENEEAL  AGEICULTUEE. 

solve  one    gram  of   solid  phosphoric   acid  in   200  c.c.  of 
water. 

Molybdate  of  ammonia.  Add  ten  grams  of  ammo- 
nium molybdate  to  25  c.c.  distilled  water ;  then  add  15  c.c. 
of  strong  chemically  pure  ammonium  hydroxid  and  150 
grams  chemically  pure  nitric  acid.  Keep  warm  and  if  a 
yellow  precipitate  appears,  pour  off  the  clear  liquid  for 
use ;  if  not  the  liquid  is  ready  for  use. 

A  saturated  solution  of  oxalate  of  ammonia.  Fill  a 
bottle  y^  full  of  ammonia  oxalate,  then  fill  with  water  and 
allow  to  stand  until  saturated  or  for  several  hours. 

1.7%  solution  of  nitrate  of  silver.  Add  1.7  grams  of 
silver  nitrate  to  100  c.c.  of  distilled  water. 

Ten  per  cent  solution  of  barium  chlorid.  Add  10 
grams  of  barium  chlorid  to  100  c.c.  of  water. 

Ten  per  cent  solution  of  ammonium  chlorid.  Add  10 
grams  of  ammonium  chlorid  to  100  c.c.  water. 

27.     DETERMINATION  OF  NITROGEN. 

Materials:  10%  caustic  potash  solution,  rubber 
pestle  made  by  placing  a  one-hole  stopper  on  the  end  of  a 
stirring  rod,  mortar,  test  tube. 

Pulverize  the  soil  with  the  rubber  pestle.  Place  7 
grams  in  a  test  tube  and  add  20  c.c.  of  caustic  potash  solu- 
tion. Boil  from  ten  to  fifteen  seconds,  then  allow  the 
heavier  portion  to  settle.  The  humus  is  dissolved  and  the 
density  of  the  color  of  the  solution  is  an  indication  of  ade- 
quacy or  inadequacy.  A  dense  black,  non-translucent 
solution  shows  the  presence  of  at  least  one  per  cent  of 
humus  in  the  soil.  A  deep  brown  translucent  color  indi- 
cates the  presence  of  about  one-half  of  one  per  cent  of 
humus.  A  light  brown  color  clearly  indicates  a  deficiency 
of  humus. 

The  test  tells  us  about  the  humus  only,  but  in  all  ex- 
cept very  arid  regions  the  humus  content  is  an  accurate 
index  of  the  nitrogen  content,  hence  the  test  is  of  prac- 
tical value. 


MANUAL  OF  OENEBAL  AGEICULTUKE.  29 

^r 

28,     DETERMINATION  OF  PHOSPHORIC  ACID. 

Materials:  Pint  of  pure  sand,  dilute  hydrochloric 
acid,  stirring  rod,  phosphoric  acid  tube.*  %%  solution 
of  phosphoric  acid,  ammonium  molybdate  solution,  funnel, 
test  tube,  filter  paper,  pan,  iron  pan  or  iron  disc,  blue  lit- 
mus paper,  beaker,  file,  millimeter  rule. 

(a)  First  prepare  a  standard  of  comparison**  by 
taking  a  pint  of  pure  sand  and  pouring  on  it  about  three 
times  its  volume  or  three  pints  of  dilute  hydrochloric  acid. 
Allow  to  stand  for  an  hour  or  more,  stirring  from  time  to 
time  with  a  strong  stirring  rod.  Place  in  the  sink  and 
allow  water  to  run  through  it  for  several  hours,  until 
water  after  being  thoroughly  stirred  up  with  it,  no  longer 
gives  any  acid  reaction  with  litmus.  Dry  the  sand  and 
take  25  grams  for  this  experiment,  saving  the  rest  for  sub- 
sequent tests.  A  good  content  of  soluble***  phosphoric  acid 
in  the  soil  is  one-tenth  of  one  per  cent.  We  will  add 
this  amount  to  the  sand  and  make  a  test.  To  the 
25  grams  of  sand  add  5  c.c.  of  a  %%  solution  of  phos- 
phoric acid.  This  gives  .025  gram  in  25  grams  of  sand  or 
.1  of  1%.  Take  two  grams  of  the  sand  which  has  been 
moistened  with  the  acid  and  burn  for  five  minutes  on  a 
red-hot  iron  for  the  purpose  of  removing  the  vegetable 
matter  or  humus.  Place  in  a  test  tube  and  add  3  or  4  c.c. 
of  pure  nitric  acid,  foat  until  it  just  begins  to  boil,  then 
add  2  or  3  c.c.  of  tap  water  and  filter  into  a  test  tube. 
Wash  out  the  acid  by  allowing  4  or  5  c.c.  of  water  to  run 
through  the  sand  into  the  filtered  liquid  and  add  to  the 
filtrate,  its  own  volume  of  a  solution  of  molybdate  of  am- 
monia. Then  place  the  test  tube  in  a  beaker  of  hot  water 

*  These  tubes  can  be  obtained  of  Justinian  Cairne  Co.,  573  Mar- 
ket St.,  San  Francisco,  California,  at  40  cents  each  or  $4.20  per 
dozen. 

**A  standard  of  comparison  is  best  made  by  taking  two  grams 
of  a  soil  in  which  the  phosphoric  acid  has  been  accurately  determined, 
instead  of  purifying  sand,  etc. 

***That  is,  soluble  in  the  acids  used  in  making  tests.  The  soil 
may  contain  a  great  deal  more  phosphoric  acid  in  insoluble  form,  but 
this  will  not  appear  in  the  test  and  is  not  directly  available  to  the 
plant. 


30  MANUAL  OF  GENERAL  AGRICULTURE. 

until  the  precipitate  has  come  down.  Pour  off  the  clear 
liquid  at  the  top  and  transfer  the  rest  to  the  phosphoric 
acid  tube.  Suppose  that  the  precipitate,  which  is 
molybdo-phosphate  of  ammonium,  when  it  has  settled  into 
the  neck  of  the  tube  forms  a  column  one  centimeter  high. 
This  would  indicate  a  content  of  .1  of  1%  of  phosphoric 
acid  in  the  soil.  With  a  file  mark  the  height  of  this  col- 
umn after  making  sure  that  the  test  is  correct  either  by 
comparison  with  tests  of  others  or  by  repeated  tests. 

(b)  Test  soil  as  follows:  Take  two  grams  of  soil, 
burn  it  on  a  red-hot  iron  for  five  minutes  or  until  it  is  light 
gray  in  color.  Place  in  a  test  tube  and  add  3  or  4  c.c. 
nitric  acid,  then  heat  until  it  just  begins  to  boil ;  add  2  or 
3  c.c.  of  water  and  filter  into  a  test  tube.  Allow  4  or  5  c.c. 
of  water  to  run  through  the  soil  into  the  filtrate  and  add 
to  the  filtrate  its  own  volume  of  ammonia  molybdate,  then 
place  the  test  tube  in  a  beaker  of  hot  water  until  the  pre- 
cipitate has  come  down.  Pour  off  the  clear  liquid  at  the 
top  and  transfer  the  rest  to  the  phosphoric  acid  tube.  If 
the  precipitate  is  above  the  standard  phosphoric  acid  mark 
we  know  that  the  soil  is  well  supplied  with  phosphoric 
acid,  i.  e.,  there  is  more  than  .1  of  1%.  Use  a  millimeter 
rule  and  calculate  the  exact  per  cent. 

29.     DETERMINATION  OF  LIME. 

Materials :  Whiting,  sand  treated  with  dilute  hydro- 
chloric acid,  test  tube,  saturated  solution  of  oxalate  of  am- 
monia, ammonium  chlorid,  file,  funnel  the  neck  of  which  is 
not  more  than  one-eighth  inch  in  diameter  and  closed  at 
the  bottom  by  heating  in  a  hot  flame,  filter  paper,  beaker, 
millimeter  rule. 

(a)  First  prepare  a  standard  of  comparison  as  fol- 
lows: To  exactly  25  grams  of  sand  previously  treated 
with  hydrochloric  acid,  add  a  quarter  of  a  gram  of  whit- 
ing, which  will  give  a  content  of  one  per  cent  of  carbonate 
of  lime  in  the  soil.  Thoroughly  mix  with  the  sand.  Place 
a  gram  of  this  sand  in  a  test  tube  and  add  1  c.c.  chem- 
ically pure  hydrochloric  acid.  Heat  until  it  just  begins  to 
boil,  then  add  ammonia  water  until  a  permanent  precipi- 


MANUAL  OF  GENEEAL  AGRICULTUKE.  31 

tate  appears.  Filter  while  hot,  then  add  a  drop  of  am- 
monium chlorid  and  1  c.c.  saturated  solution  of  oxalate  of 
ammonia.  Transfer  to  the  closed  funnel  and  allow  the 
precipitate  of  oxalate  of  lime  to  settle.  Suppose  the  pre- 
cipitate forms  a  column  2  c.m.  high.  This  would  indicate 
a  content  of  1%  of  carbonate  of  lime.  With  a  file  mark 
the  height  of  this  column  after  verifying  your  result, 
either  by  comparing  with  tests  of  others,  or  by  repeated 
tests.  The  height  of  this  mark  becomes  the  standard  of 
comparison  for  future  tests. 

(b)  Test  samples  of  soil  in  a  similar  way  as  follows : 
Place  one  gram  of  soil  in  a  test  tube.  Add  1  c.c. 
hydrochloric  acid  and  heat  until  it  just  begins  to  boil. 
Add  strong  ammonia  until  a  permanent  precipitate 
appears ;  filter  while  hot,  add  a  drop  of  ammonium  chlorid 
and  1  c.c.  of  a  saturated  solution  of  oxalate  of  ammonia. 
Transfer  to  the  closed  funnel  and  allow  the  precipi- 
tate to  settle.  Calculate  the  per  cent  of  lime  by  using  a 
millimeter  rule.  Our  standard  indicates  a  lime  content  of 
one  per  cent.  In  a  clay  soil  1  to  2%  is  about  right.  In  a 
sandy  soil  three-tenths  to  five-tenths  of  one  per  cent  is 
good.  Ten  to  fifteen  per  cent  is  an  excess  in  any  soil. 

30.     DETERMINATION  OF  ALKALI. 

Materials:  Sand,  sodium  carbonate,  sodium  chlorid, 
sodium  sulphate,  filter  and  litmus  paper,  nitric  acid,  silver 
nitrate  solution,  barium  chlorid,  and  phosphoric  acid  tube. 

(a)  Prepare  a  standard  of  comparison  as  follows: 
To  20  grams  of  sand  which  has  been  treated  with  hydro- 
chloric acid,  add  4  c.c.  of  a  solution  made  by  dissolving 
in  100  c.c.  of  distilled  water  1  gram  of  sodium  carbonate, 
1  gram  sodium  chlorid  and  3.3  grams  sodium  sulphate. 
This  gives  a  content  in  the  soil  of  one-tenth  of  one  per  cent 
sodium  carbonate,  two-tenths  of  one  per  cent  sodium 
chlorid  (common  salt),  and  three-tenths  of  one  per  cent 
sodium  sulphate.  These  are  all  excessive  and  harmful 
amounts  and  a  soil  which  contains  as  much  of  any  is  un- 
suitable for  ordinary  crops. 


32  MANUAL  OF  GENEEAL  AGBICULTUKE. 

(b)  Test  the  standard  sample  and  then  20  grams 
each  of  several  samples  of  alkali  soils  as  follows:  Place 
filter  paper  in  a  funnel  and  put  the  sand  or  soil  on  it ;  add 
20  c.c.  of  water  and  let  it  leach  through  into  a  beaker,  then 
divide  the  leachings  into  two  equal  parts.  Divide  one  part 
into  fourths,  dilute  three  of  them  with  one,  two  and  three 
volumes  of  water  respectively. 

1.  Sodium  Carbonate.    Test  the  undiluted  part,  then 
each  diluted  part  with  red  litmus  paper.     The  rapidity 
with  which  the  paper  turns  blue  indicates  the  amount  of 
black  alkali  or  sodium  carbonate.    If  it  quickly  turns  deep 
blue  it  indicates  an  excessive  amount;  one-tenth  of  one 
per  cent  or  more.    If  it  turns  blue  very  slowly  it  indicates 
a  lesser  amount.    Save  the  original  samples  as  a  standard 
of  comparison  for  samples  of  soil  and  label  each. 

2.  Sodium  Chlorid.    Take  half  of  the  unused  leach- 
ings  and  test  for  common   salt    as   follows:     Add  a  few 
drops  of  nitric  acid  and  then  a  drop  or  two  of  a  1.7  per 
cent  solution  of  silver  nitrate,  a  white  curdy  precipitate 
of  silver  chlorid,  shows  an  excessive  amount  of  salt  (two- 
tenths  of  one  per  cent  or  more)  and  from  this  we  may  find, 
in  testing  soils,  all  amounts  down  to  a  trace  which  gives 
only  a  slight  milkiness  on  the  addition  of  silver  nitrate. 

3.  Sodium  Sulphate.  Take  the  remainder  of  the  leach- 
ings  and  test  for  sodium  sulphate  as  follows :   Add  a  few 
drops  of  hydrochloric  acid,  heat,  then  add  a  few  drops  of 
barium  chlorid  to  the  hot  solution.    Transfer  to  the  phos- 
phoric acid  tube  and  in  the  case    of   the    prepared  sand 
mark  the  height  of  the  column   of   precipitate    which  is 
barium  sulphate.    This  indicates  a  content  of  three-tenths 
of  one  per    cent,  which    is    an    excessive    and    injurious 
amount.     With  this  as  a  standard  we  may  calculate  the 
amount  of  sodium  sulphate  in  soil  samples.    (Record  the 
sodium  sulphate  mark  as  before,  to  be  used  as  a  standard.) 


MANUAL  OF  GENEEAL  AGEICULTUEE.  33 

PART  III— CHEMISTRY  OF  PLANTS. 

31.     MOISTURE  IN  THE  PLANT. 
Materials:     A  small  pan  with  a  capacity  of  100  to 
150  c.c.,  a  balance  sensitive  to  10  milligrams,  drying  oven, 
thermometer. 

Dry  the  pan  and  weigh  it  carefully.  Nearly  fill  it 
with  finely  cut  stems  and  leaves  of  a  fresh  plant  that  is 
growing  vigorously.  Weigh  again.  Kecord  all  weights. 
Get  the  weight  of  the  plant  material  by  the  difference. 
Place  the  pan  in  the  oven  and  keep  the  temperature  at  100 
to  105  degrees  C.  for  five  or  six  hours.  Cool  and  weigh. 
Heat  in  the  oven  again  for  an  hour  and  cool  and  weigh. 
If  the  weight  is  constant,  the  material  is  dry.  If  there  is 
an  appreciable  difference  shown  by  the  two  weighings, 
repeat  the  heating,  cooling,  and  weighing  till  a  constant 
weight  is  shown.  The  total  loss  in  weight  represents  the 
amount  of  water  held  mechanically  in  the  plant.  Calcu- 
late the  amount  in  per  cent  of  the  original  weight  of  the 
plant  material.  Our  ordinary  growing  plants  hold  75  to 
95%  of  water  in%  this  way.  Save  the  dry  material  for 
Exercises  32  and  34. 

32.     COMPOSITION  OF   DRY   MATTER   OF  PLANTS. 

Materials:  Porcelain  crucible,  250  c.c.  flask,  wire 
triangle,  iron  tripod  or  ring  stand. 

Nearly  fill  the  crucible  with  dried  plant  material  and 
heat  it  over  the  burner  till  the  substance  begins  to  blaze. 
Remove  the  burner  and  quickly  hold  over  the  blazing  ma- 
terial a  flask,  nearly  full  of  cold  water  and  clean  and  dry 
on  the  outside.  Note  the  condensation  of  water  on  the 
cold  surface  of  the  flask.  As  the  material  used  was  dry, 
this  water  must  have  been  produced  by  the  breaking  up 
of  the  plant  tissues.  It  consists  of  oxygen  and  hydrogen, 
two  elements  of  plant  composition.  This,  as  well  as  the 
mechanically  held  water,  was  derived  from  the  soil  water, 
having  risen  through  the  roots.  Remove  the  flask  and  ob- 
serve the  charred  mass  remaining  in  the  crucible.  It  is 
principally  carbon  derived  from  the  air.  Continue  to  heat 


34  MANUAL  OF  GENEEAL  AGEICULTUEE. 

the  crucible  until  there  remains  a  light,  gray  colored  ash. 
These  ashes  show  the  part  of  the  plan  that  is  derived 
from  the  soil.  How  does  it  compare  with  the  part  derived 
from  the  water  and  air  (the  part  that  has  burned  away)  ? 
Save  the  plant  ash  for  Exercise  33. 

The  average  plant  derives  about  9.0%  of  its  weight 
from  the  air,  89.5%  from  the  water  and  1.5%  from  the 
soil.  The  air  always  supplies  its  portion  to  the  plant 
without  assistance  of  the  farmer ;  our  California  soils  are 
generally  quite  fertile  and  with  proper  cultivation  will 
usually  yield  their  portion  of  the  food ;  but  to  supply  the 
large  amount  of  water  that  the  plant  soil  requires,  offers 
a  problem  that  is  becoming  very  serious,  and  one  to  which 
we  are  prone  not  to  give  proper  consideration. 

33.     COMPOSITION  OF  PLANT  ASH. 

Materials:  Evaporating  dish,  funnel,  niters,  test 
tubes,  three  inches  of  platinum  wire  (fine  iron  wire  may 
be  used),  cobalt  blue  glass  (or  a  blue  glass  bottle),  glass 
stirring  rod,  concentrated  hydrochloric  acid,  concentrated 
nitric  acid,  distilled  water,  solutions  of  potassium  sulpho- 
cyanate,  sodium  phosphate,  silver  nitrate,  barium  chlorid, 
ammonium  molybdate,  and  ammonia. 

Place  in  an  evaporating  dish  about  y2  gram  of  the 
plant  ash  left  from  the  previous  exercise.  Add  to  it  5  c.c. 
each  of  distilled  water  and  concentrated  hydrochloric  acid 
and  a  few  drops  of  concentrated  nitric  acid.  A  rapid  froth- 
ing, or  effervescence,  when  the  acid  is  added,  proves  that 
carbon  is  a  constituent  of  the  ash.  Heat  the  mixture  to  boil- 
ing and  evaporate  it  nearly  to  dryness.  Add  10  c.c.  distilled 
water  and  stir  well  with  a  glass  rod.  The  small  amount 
of  white  insoluble  matter  contains  the  silicon  of  the  ash. 
Filter  and  wash  the  residue  on  the  filter  with  a  little  dis- 
tilled water  and  add  the  washings  to  the  filtrate.  To  this 
add  ammonia  with  constant  stirring  till  the  solution  smells 
strongly  of  ammonia,  and  heat  to  boiling.  Filter  and 
wash  the  residue  as  above  and  save  the  filtrate  and  wash- 


MANUAL  OF  GENEEAL  AGEICULTUEE.  35 

ings  to  test  for  calcium.  To  the  residue  on  the  filter  add 
a  few  drops  of  hydrochloric  acid,  and  to  the  liquid  that 
passes  through  add  a  drop  of  potassium  sulpho-cyanate 
solution.  A  red  color  proves  iron.  Heat  to  boiling  the 
filtrate  saved  to  test  for  calcium  and  add  5  c.c.  ammo- 
nium oxalate  solution.  A  milky  white  precipitate  shows 
calcium  in  the  ash.  Filter  and  wash  as  above  and  divide 
the  filtrate  and  washings  into  two  parts.  To  one  part  add 
slowly  drop  by  drop  5  c.c.  sodium  phosphate  solution. 
Add  5  c.c.  strong  ammonia.  A  white  precipitate  forming 
on  standing  (immediately  if  there  is  much  magnesium) 
proves  magnesium  a  constituent  of  the  plant  ash.  Place 
the  remaining  half  of  the  above  solution  in  an  evaporat- 
ing dish.  Evaporate  to  dryness  and  heat  to  a  dull  redness 
if  possible,  or  till  white  vapors  no  longer  come  off.  Cool 
and  add  to  the  residue  a  drop  or  two  of  hydrochloric  acid. 
Heat  a  platinum  wire  in  a  colorless  gas  flame  till  it  gives  no 
yellow  color  to  the  flame.  Dip  the  wire  into  the  residue 
and  again  heat  it  in  the  colorless  flame.  A  bright  yellow 
color  imparted  to  the  flame  proves  sodium.  Repeat  the 
above  platinum  wire  test,  observing  it  through  a  dark 
blue  glass  or  a  blue  bottle  that  will  shut  out  the  yellow 
color.  A  violet  color,  visible  only  through  the  blue  glass, 
proves  potassium  to  be  in  the  ash. 

To  a  fresh  portion  of  about  half  a  gram  of  plant  ash 
add  5  c.c.  each  of  distilled  water  and  strong  nitric  acid. 
Heat  to  boiling,  add  10  c.c.  more  of  distilled  water  and 
filter.  Divide  the  filtrate  into  three  parts.  To  one  part 
add  2  c.c.  silver  nitrate  solution.  A  white  precipitate,  or 
a  milkiness  imparted  to  the  solution,  proves  chlorin  in 
the  ash.  To  the  second  add  5  c.c.  ammonium  molybdate 
solution  and  heat  to  blood  temperature.  Let  stand  for  a 
while  and  a  yellow  precipitate  will  prove  phosphorus  in 
the  ash.  To  the  last  portion  add  2  c.c.  barium  chlorid 
solution.  A  white  precipitate  or  a  milkiness  proves  sul- 
phur. 


36  MANUAL  OF  GENERAL  AGRICULTURE. 

34.     NITROGEN  IN  PLANTS. 

Materials:  Hard  glass  test  tube,  one-hole  stopper  to 
fit  test  tube,  glass  and  rubber  tubing  for  delivery  tube, 
litmus  paper,  test  tube,  soda-lime.* 

Mix  a  gram  of  the  dried  plant  material  from  Exercise 
31  with  ten  grams  soda-lime.  Place  the  mixture  in  a 
hard  glass  test  tube  about  an  inch  in  diameter.  Close  the 
tube  with  the  one  hole  stopper  connected  with  a  delivery 
tube  that  dips  into  a  test  tube  of  distilled  water  in  which 
is  placed  a  few  small  pieces  of  red  litmus  paper.  Apply 
strong  heat  to  the  hard  glass  test  tube  for  four  or  five 
minutes  or  more.  Ammonia  is  formed  from  the  plant 
nitrogen  and  this  passing  over  dissolves  in  the  water.  If 
the  litmus  paper  turns  blue  it  is  a  proof  that  the  plant 
contained  nitrogen. 

35.     PLANT  NUTRITION. 

Materials :  Ten  glass  tumblers,  wrapping  paper,  par- 
affin, large  pan,  easily  bent  wire,  six  vessels  that  will  hold 
over  500  c.c.  each,  100  Canadian  field  peas  germinated  in 
moist  sawdust,  six  quarts  of  distilled  water,  2  grams  of 
calcium  nitrate,  1  gram  potassium  nitrate,  .5  gram  mag- 
nesium sulphate,  .5  gram  potassium  acid  phosphate,  1 
gram  sodium  acid  phosphate,  .5  gram  sodium  nitrate,  .5 
gram  sodium  chlorid,  .1  gram  sodium  sulphate,  .1  gram 
magnesium  chlorid. 

For  demonstrating  the  necessary  elements  for  plant 
growth,  water  cultures  are  employed.  A  water  culture 
containing  the  elements,  nitrogen,  phosphorous,  potas- 
sium, calcium,  magnesium,  sulphur  and  iron,  in  the  form 
of  soluble  compounds  (salts)  dissolved  in  distilled  water 
will  afford  more  or  less  perfect  growth.  This  kind  of 
water  culture  is  known  as  a  full  nutrient  solution.  These 
seven  elements,  in  addition  to  hydrogen  and  oxygen  found 
in  water,  and  carbon,  supplied  by  the  carbon  dioxid  of  the 
air,  are  those  necessary  for  green  plants  generally. 

*Soda-lime  is  a  mixture  of  caustic  soda  and  quick  lime, 
obtainable  in  tight  bottles;  it  forms  an  eager  absorbent  of  carbon 
dioxid. 


MANUAL  OF  GENERAL  AGRICULTURE.  37 

The  absence  of  any  one  will  be  readily  shown  in  the 
growth  of  the  plant.  As  the  seed  contains  a  considerable 
amount  of  plant  food,  no  marked  difference  in  growth  may 
be  noted  the  first  few  days,  even  though  one  or  more  of 
the  necessary  elements  be  absent.  Where  the  necessity 
of  an  element  is  to  be  determined  it  is  omitted  from  the 
water  culture  and  replaced  by  some  unnecessary  com- 
pound. 

For  the  cultures  obtain  10  glass  tumblers  and  make  a 
cover  of  paraffined  paper  for  each  by  dipping  ordinary 
wrapping  paper  into  a  pan  of  melted  paraffin.  The  paper 
may  be  held  in  place  by  a  string  tied  around  the  side  of 
the  tumbler.  Do  not  tie  on  the  covers  until  directed. 

Thoroughly  clean  six  vessels  and  make  up  the  follow- 
ing stock  nutrient  solutions : 

For  calcium  and  nitrogen  use  calcium  nitrate,  2  grams 
in  500  c.c.  distilled  water. 

For  potassium  and  nitrogen  use  potassium  nitrate,  % 
gram  in  500  c.c.  distilled  water. 

For  magnesium  and  sulphur  use  magnesium  sulphate, 
1/2  gram  in  500  c.c.  distilled  water. 

For  potassium  and  phosphorous  use  potassium  hydro- 
gen phosphate,  1/2  gram  in  500  c.c.  distilled  water. 

For  potassium  (in  different  form  than  above)  use 
potassium  chlorid,  *4  gram  in  500  c.c.  distilled  water. 

For  iron  use  ferric  chlorid,  two  drops  in  500  c.c.  dis- 
tilled water. 

Equal  quantities  of  the  above  solutions  taken  will 
give  a  full  nutrient  solution  in  proper  proportions. 

Set  up  the  following  series  of  cultures: 

I.  One  culture  in  distilled  water. 

II.  One  culture  in  tap  water. 

III.  One  culture  in  full  nutrient  solution.     (Use  40  c.c. 

each  of  the  six  solutions  prepared.) 

IV.  One  culture  in  full  nutrient  solution  minus  nitrogen 

(1)  For  calcium  nitrate  substitute  40  cc.  calcium 
chlorid  made  by  dissolving  .4  gram  in  100  cc.  dis- 
tilled water. 


38  MANUAL  OF  GENERAL  AGRICULTURE. 

(2)  For  calcium  nitrate  substitute  40  cc.  potassium 
chlorid  made  by  dissolving  .1  gram  in  100  cc.  (Save 
the  remainder  for  V.) 

V.  One   culture   in  full   nutrient   solution   minus   phos- 

phorous. For  potassium  hydrogen  phosphate  sub- 
stitute 40  cc.  potassium  chlorid  made  in  IV  (2.) 

VI.  One  culture  in  full  nutrient  solution  minus  potas- 

sium. 

(1)  For  potassium  hydrogen  phosphate  substitute 
40  cc.  sodium  hydrogen  phosphate  made  by  dis- 
solving .1  gram  in  100  cc.  distilled  water. 
(2.)  For  potassium  nitrate  substitute  40  cc.  sodium 
nitrate  made  by  dissolving  .1  gram  in  100  cc.  of 
distilled  water. 

(3)  For  potassium  chlorid  substitute  40  cc.  sodium 
chlorid  made  by  dissolving  .4  gram  in  100  cc.  dis- 
tilled water. 

VII.  One  culture  in  full  nutrient  solution  minus  calcium. 

For  calcium  nitrate  substitute  40  cc.  sodium  ni- 
trate in  the  proportion  .4  gram  in  100  cc.  distilled 
water. 

VIII.  One  culture  in  full  nutrient  solution  minus  mag- 
nesium. 

For  magnesium  sulphate  substitute  40  cc.  sodium 
sulphate  made  by  dissolving  .1  gram  in  100  cc.  dis- 
tilled water. 

IX.  One  culture  in  full  nutrient  solution  minus  sulphur. 

For  magnesium  sulphate  substitute  40  cc.  magne- 
sium chlorid  made  by  dissolving  .1  gram  in  100 
cc.  distilled  water. 

X.  One  culture  in  full  nutrient  solution  minus  iron. 

For  ferric  chlorid  substitute  40  cc.  sodium  chlorid 
made  by  dissolving  a  trace  in  500  cc.  distilled  water. 

Place  the  covers  over  each  of  the  ten  tumblers  and 
tie  them  securely  in  place.    Punch  ten  holes  in  each  cover 


MANUAL  OF  GENERAL  AGEICULTUEE.  39 

large  enough  for  the  roots  of  the  previously  germinated 
Canada  field  peas  to  go  through.  Select  100  of  the  most 
vigorous  plants  and  arrange  ten  in  each  tumbler  so  that 
the  roots  are  below  and  tops  above  the  covers.  In  about 
two  weeks  it  will  be  necessary  to  make  a  wire  frame  to 
support  the  plants.  Place  the  tumblers  in  a  sunny  place 
and  allow  the  culture  to  grow  four  weeks.  During  this 
period  every  few  days  add  distilled  water  so  that  the 
quantity  of  the  solution  remains  about  the  same. 

Make  notes  weekly  concerning  the  general  vigor  of 
the  cultures.  Final  notes  should  include  (1)  Average 
length  of  tops  and  of  roots  of  each  culture,  (2)  Green 
weignts  of  tops  and  of  roots. 

36.     NITROGEN  NODULES. 

Go  out  and  dig  up  (without  injury  to  the  roots)  a 
specimen  of  as  many  of  the  following  as  are  conveniently 
near:  a  bean,  a  pea,  a  clover,  an  ailaila,  a  lupine.  These 
plants  all  belong  to  the  same  family,  "leguinmosge,"  and 
are  commonly  called  "legumes."  Examine  the  roots  for 
very  small  knots  called  "nodules."  Also  dig  up  the 
roots  of  some  cereals  and  examine  them  for  nodules.  Do 
you  find  any?  Draw  one  root  system  showing  nodules. 

The  nodules  are  the  home  of  bacteria.  (See  Exercise 
65,  first  paragraph.)  These  minute  organisms  are  able 
to  use  the  free  nitrogen  of  the  soil  air  and  combine  it 
with  the  mineral  matter  of  the  soil  to  form  nitrates.  The 
plant  cannot  use  free  nitrogen  but  flourishes  on  the  ni- 
trates which  the  bacteria  offer  in  return  for  the  home  pro- 
vided by  the  legume.  The  plant  satisfies  its  needs  from 
the  nitrates  thus  produced  and  any  excess  remains  in  the 
soil  for  future  crops.  This  suggests  a  reason  for  crop 
rotation  practice  of  following  a  legume  crop  (a  nitrogen 
food  producer)  by  a  cereal  crop  (a  nitrogen  food  con- 
sumer.) 


40  MANUAL  OF  GENERAL  AGRICULTURE. 

37.    TEST  FOR  THE  PRINCIPAL  CLASSES  OF 
PLANT  COMPOUNDS. 

Materials:  Knife,  test  tube,  iodine  solution*,  Fehl- 
ing's  solutionf,  10%  solution  copper  sulfate,  10%  solu- 
tion potassium  hydroxid,  evaporating  dish. 

(a)  Carbohydrates.     Starch.     Cut  a  small  potato  in 
half.    Peel  and  cut  into  small  slices  or  rub  on  an  ordinary 
grater  a  small  portion  and  collect  the  pieces  or  gratings 
in  a  small  dish  of  cool  water.    Boil  and  allow  the  solution 
to  cool.    Add  a  drop  of  iodine.    A  deep  blue  color  proves 
the  presence  of  starch.     To  another  piece  of  potato  add 
a  drop  of  iodine.    Eesult? 

Sugar.  Cut  another  piece  of  potato  into  very  thin 
slices  and  place  in  a  test  tube.  Test  for  grape  sugar  with 
Fehling's  solution  as  follows:  Measure  out  2  c.c.  of  solu- 
tion 1,  and  add  to  it  5  c.c.  of  solution  2,  and  3  c.c.  of 
water.  Add  this  to  the  test-tube  containing  the  potato 
and  boil  two  or  three  minutes.  A  red  precipitate  (sedi- 
ment) indicates  the  presence  of  grape  sugar.  If  the  red 
precipitate  does  not  appear  soon,  allow  the  boiled  solu- 
tion to  stand  until  next  laboratory  period. 

There  is  no  elementary  test  for  cane  sugar. 

(b)  Proteids.    Cut  cross  section  of  beans  and  potato 
and  carefully  touch  the  cuts  with  a  glass  rod  that  has 
been  dipped  in  nitric  acid.    A  yellow  color  should  appear 
which  will  become  more  intensely  yellow  if  ammonia  is 
applied.     Try  it.     This  coloration  is  due  to  the  action  of 
the  chemicals  on  the  proteids  in  the  substances  tested. 

Optional  test.  Pour  a  small  quantity  of  the  white 
of  an  egg,  which  is  a  good  example  of  protein,  in  an 
evaporating  dish,  and  barely  cover  with  a  10%  solution 

*Iodin  solution  is  prepared  by  dissolving  potassium  iodide  in 
water  (about  one  part  to  seventy-five  of  water)  and  adding  iodine 
crystals  until  the  solution  becomes  dark  brown  in  color. 

tFehling's  solution  is  made  by  dissolving  34.65  grams  of 
copper  sulfate  in  200  c.c.  of  water  to  make  solution  1.  To  make 
2,  dissolve  173  grams  of  sodium  potassium  tartrate  (Rochelle  Salt) 
in  480  c.c.  of  a  ten  per  cent  solution  of  sodium  hydroxid.  Use  as 
directed  in  the  experiment,  making  up  the  reagent  fresh  when- 
ever needed. 


MANUAL  OF  GENEEAL  AGEICULTUEE.  41 

of  caustic  potash  (potassium  hydroxid.)  Warm  but  do 
not  cook  the  egg.  Add  a  few  drops  of  a  10%  solution 
of  blue  stone  (copper  sulfate)  and  let  stand  until  next 
laboratory  period.  At  first  a  greenish  blue  color  appears 
and  in  ten  or  fifteen  minutes  a  beautiful  violet  color  proves 
the  presence  of  proteids. 

(c)  Fats  and  Oils.  Grind  a  tablespoonful  of  oats, 
barley,  or  corn.  If  the  grinding  cannot  be  conveniently 
done  use  bran,  flaxseed,  or  any  ground  feed.  Place  in  a 
bottle  and  pour  over  it  15  c.c.  of  ether$.  Stopper,  shake 
well  at  intervals  for  half  an  hour  or  let  stand  until  the 
next  laboratory  period.  Filter  the  liquid  into  a  clean 
evaporating  dish  and  allow  the  ether  to  evaporate  in  the 
open  air.  The  residue  is  plant  fat  and  oil. 

38.     OCCURRENCE  AND  EXTRACTION  OF  STARCH. 

Materials:  Compound  microscope,  piece  of  potato, 
grater,  beaker,  evaporating  dish,  test  tube  holder,  glass 
tube  8  in.  long,  lime  water,  ring-stand,  one-hole  rubber 
stopper  for  test  tube,  cheesecloth. 

(a)  Examine    a   thin   section   of   potato   under   the 
microscope.     Make  a  careful   drawing  of  the   structure 
of  the  cells  and  granules  within.     Cover  the  section  with 
a   cover   glass   and  introduce   a  minute   trace   of  iodine 
solution  at  the  edge  of  the  cover  glass.     Make  a  shaded 
or  colored   (blue  pencil)   drawing  of  the  object. 

(b)  Clean  and  peel  one  end  of  a  potato.     Rub  it  on 
a  grater  and  collect  the  gratings    in    a    beaker    of    cold 
water.    Strain  through  a  cheesecloth  and  allow  the  cloudy 
liquid  to  stand  until  the  starch  settles.    Pour  off  some  of 
the  liquid  and  evaporate   some   of  it  to   dryness  in  an 
evaporating  dish.     Describe  the  residue. 

Heat  a  small  portion  of  starch  in  a  test  tube.  What 
does  this  show  starch  to  contain?  Take  another  test  tube 
and  fill  it  one-third  full  of  lime  water.  Insert  into  the 
test  tube  containing  the  starch  a  one-hole  rubber  stopper. 
Bend  a  glass  tube  8  inches  long  into  a  right  angle,  and 

JDo  not  place  ether  near  a  flame. 


42  MANUAL  OF  GENERAL  AGRICULTURE. 

insert  one  end  into  the  stopper  and  the  other  end  into  the 
lime  water,  arranging  the  apparatus  on  a  ring-stand. 
Gently  heat  the  starch  in  the  test  tube.  The  milky  ap- 
pearance of  the  lime-water  indicates  the  presence  of 
carbon  dioxid  in  starch.  Test  the  breath  for  carbon 
dioxid  gas  by  blowing  through  a  tube  into  a  test  tube 
one-third  full  of  clear  lime  water. 

Questions:  1.  What  two  compounds  does  starch 
contain  ?  2.  What  three  elements  does  starch  contain  ?  3. 
To  what  class  of  plant  compounds  does  starch  belong,  or- 
ganic or  inorganic  ? 

39.     INVERSION  OF  CANE  SUGAR  (SUCROSE). 

Materials:  Cane  sugar,  evaporating  dish,  sulphuric 
acid,  sand  bath,  Fehling's  solution,  calcium  carbonate,  fil- 
ter paper,  funnel. 

There  is  no  direct  simple  test  for  cane  sugar  but  by 
changing  the  cane  sugar  to  grape  sugar  we  get  an  indirect 
test.  This  change  is  known  as  inversion  of  cane  sugar. 

Place  2  grams  of  sugar  in  an  evaporating  dish  and 
add  30  c.c.  of  water  and  2  c.c.  of  sulphuric  acid.  Heat 
fifteen  minutes  on  a  sand  bath,  replacing  the  water  lost 
by  evaporation.  Neutralize  with  calcium  carbonate.  De- 
termine when  neutral  by  using  litmus  paper.  Add  more 
water  for  filtration  if  necessary.  Test  with  Fehling's 
solution.  Result  ? 

Take  one-tenth  gram  of  cane  sugar,  dissolve  in  10  c.c. 
of  cold  water  and  test  with  Fehling's  solution.  Result? 

Question:  1.  What  is  the  object  of  adding  calcium 
carbonate  ? 

40.  PREPARATION  OF  GLUCOSE  (GRAPE  SUGAR.) 

Materials:  Evaporating  dish,  sand  bath,  starch,  cal- 
cium carbonate,  litmus  paper,  iodin  solution,  filter,  stir- 
ring rod,  Fehling's  solution. 

Add  10  drops  of  sulphuric  acid  to  about  35  c.c.  of  wa- 
ter in  an  evaporating  dish.  Heat  on  a  sand  bath  until  the 
boiling  point  is  reached.  Add  1  gram  of  pulverized  starch, 
noting  its  appearance  immediately  after  adding.  Heat  25 


MANUAL  OF  GENEEAL  AGEICULTUEE.  43 

minutes,  stirring  occasionally,  and  replacing  water  should 
too  much  evaporate.  Add  calcium  carbonate  to  neutral- 
ize the  sulphuric  acid.  Determine  when  neutral  by  using 
litmus  paper.  "When  neutral  filter  and  wash  the  residue 
with  15  c.c.  of  water.  Test  a  few  drops  of  the  nitrate  with 
iodin.  Have  the  properties  of  the  starch  been  destroyed  ? 
Evaporate  the  remainder  in  an  evaporating  dish  to  about 

10  c.c.     Test  for  glucose  or  grape  sugar  with  Fehling's 
solution. 

41.     ESSENTIAL  OIL  FROM  PLANTS. 

Materials :  Tea,  clover,  or  alfalfa,  glass  stoppered  re- 
tort (as  used  in  preparation  of  nitric  acid),  large  test  tube, 
wire  gauze. 

Place  5  grams  of  tea  into  the  glass  stoppered  retort 
and  add  50  c.c.  water.  Place  the  end  of  the  retort  in  a 
test  tube  one-third  full  of  water.  Support  the  apparatus 
on  a  ring  stand,  allowing  the  retort  to  rest  on  a  wire 
gauze.  Apply  heat  and  distill  3  or  4  c.c.  Observe  the 
color  of  the  distillate  (in  the  test  tube.)  Is  the  essential 

011  from  tea  volatile  ?    Repeat  the  experiment,  using  clover 
or  alfalfa. 

42.     EXTRACTION  OF  PROTEIDS. 

Materials:  Flour,  cheesecloth,  pan,  10%  solution  of 
sodium  chlorid,  test  tube. 

A  good  illustration  of  protein  is  gluten,  obtained  from 
wheat  flour.  Mix  in  a  pan  with  a  glass  rod  30  grams  of 
flour  and  sufficient  water  to  make  a  stiff  dough  and  let 
stand  half  an  hour  in  order  that  the  physical  properties  of 
the  gluten  may  develop.  Place  in  a  cheesecloth  and  wash 
in  a  stream  of  water,  working  the  dough  gently  with  the 
fingers. 

Continue  washing  until  the  water  runs  away  clear, 
which  indicates  that  all  the  starch  has  been  washed  out. 
The  gluten  remains  on  the  cheesecloth.  Treat  a  small  por- 
tion of  gluten  with  a  10%  solution  of  sodium  chlorid. 
Does  it  dissolve? 

In  California  there  are  no  definite  divisions  between 
winter  and  spring  wheats.  But  in  localities  where  this 


44  MANUAL  OF  GENERAL  AGRICULTURE. 

distinction  is  marked,  or  where  flour  from  winter  and 
spring  wheats  can  be  obtained,  treat  a  sample  of  each  as 
indicated,  and  compare  the  two. 

43.  EXTRACTION  AND  DECOMPOSITION  OF 

CHLOROPHYLL. 

Materials:  Green  leaves,  preferably  of  young  grow- 
ing grass  or  cereal,  large  test  tube,  two  small  test  tubes. 

Place  some  green  leaves  into  a  large  test  tube,  filling 
the  tube  about  one-third  full.  Pour  alcohol  over  them 
until  the  test  tube  is  about  one-half  full.  Boil  for  about 
two  minutes.  Transfer  the  liquid  to  two  small  test  tubes, 
pouring  the  same  amount  into  each.  Note  the  color  of  the 
chlorophyll  extract. 

Place  one  solution  in  direct  sunlight  and  the  other  in 
complete  darkness.  At  the  end  of  an  hour  and  again  at 
the  next  meeting  compare  the  two. 

Questions:  1.  What  is  chlorophyll?  2.  What  is 
the  effect  of  light  on  chlorophyll  ? 

44.  DETERMINATION  OF  OIL  IN  FLAXSEED. 

Materials :  Ground  flaxseed,  ether  or  benzine,  evapo- 
rating dish,  filter,  filter  paper,  ring  stand. 

(a)  Weigh  out  25  grams  of  flaxseed  and  add  25  c.c. 
of  ether  or  benzine.*  Let  stand  about  fifteen  minutes  and 
then  filter  into  an  evaporating  dish.  Wash  the  meal  by 
pouring  over  it,  a  little  at  a  time,  about  the  same  amount 
of  ether  or  benzine.  Let  the  liquid  stand  in  a  good  draft 
until  the  next  laboratory  period  or  until  it  has  lost  the 
odor  of  the  liquid  used.  Weigh  the  remaining  oil  (fat) 
and  calculate  what  per  cent  of  the  ground  seed  was  oil. 
(A  small  amount  of  fat  will  still  be  left  in  the  residue.) 

(1)  Describe  the  oil  obtained.  (2)  Of  what  use 
would  it  have  been  to  the  plant  ? 

Optional.  Oil  from  yolk  of  egg.  Repeat  the  above 
experiment,  using  10  grams  of  the  yolk  of  a  hard-boiled 
egg  and  add  10  c.c.  of  ether  or  benzine. 

*Do  not  bring  ether  or  benzene  near  a  flame. 


MANUAL  OF  GENERAL  AGEICULTUEE.  45 

(1)  Compare  the  appearance  of  this  oil  (fat)  with 
that  from  flaxseed.  Are  the  oils  in  flaxseed  and  the  yolk 
of  an  egg  volatile  ? 

45.     ABSORPTION  OF  MANURE  BY  THE  SOIL. 

Materials :  A  pan,  a  tall  quart  can,  a  large  funnel,  n, 
beaker  and  quart  of  well  rotted  stable  manure. 

Soak  a  quart  of  well  rotted  stable  manure  for  two 
days  in  enough  water  to  cover  it.  Perforate  the  bottom 
of  a  tall,  narrow  can,  holding  about  a  quart,  and  fill  it 
with  dry  soil.  Set  it  in  a  large  funnel.  Pour  off  the  water 
from  the  manure  and  note  its  color.  A  large  part  of  the 
fertilizing  value  of  the  manure  has  dissolved  in  the  water. 
This  suggests  that  the  practice  of  piling  manure  in  heaps 
and  letting  it  lay  exposed  to  the  leaching  action  of  the 
winter  rains  is  a  very  wasteful  one.  Slowly  pour  the  ma- 
nure water  over  the  soil  and  let  it  drain  through  into  a 
beaker.  Compare  the  color  of  the  drainage  with  that 
before  adding  it  to  the  soil.  Has  the  soil  absorbed  the  val- 
uable part  of  the  manure  ?  A  common  practice  is  to  pile 
a  load  of  manure  in  a  place,  throughout  the  field,  and  scat- 
ter the  piles  after  they  have  rotted  all  winter.  Will  this 
give  an  even  distribution  of  the  fertilizing  part  of  the 
manure  ? 

46.     FERTILIZER  FIELD  TESTS. 

This  set  of  tests  should  be  carried  on  in  co-operation 
with  some  progressive  farmer  whose  farm  is  near  the 
school.  Select  a  field  that  is  not  yielding  well.  Lay  out 
the  field  of  uniform  soil,  or  as  nearly  as  may  be,  in  plats 
of  2  rods  or  33  feet  by  4  rods  or  66  feet.  There  will  be 
one-twentieth  of  an  acre  in  each  plat.  Put  stakes  at  the 
corners  and  keep  an  accurate  record  as  to  treatment. 
When  the  soil  is  thoroughly  prepared,  and  just  before 
seeding,  apply  the  fertilizers  by  sowing  them  broadcast, 
being  careful  that  all  parts  of  the  plat  receive  the  same 
quantity  of  fertilizers.  The  eight  plats  should  be  fertil- 
ized as  follows : 


46  "  MANUAL  OF  GENERAL  AGRICULTURE. 

No.  1.     No  fertilizer,  serving  as  a  check. 

No.  2.  10  Ibs.  sulphate  of  potash.  (Approximate 
cost  4c  per  Ib.) 

No.  3.     20  Ibs.  acid  phosphate.     (l%c  per  Ib.) 

No.  4.     10  Ibs.  nitrate  of  soda,  .(3c  per  Ib.) 

No.  5.     10  Ibs.  nitrate  of  soda,  20  Ibs.  acid  phosphate. 

No.  6.  10  Ibs  nitrate  of  soda,  10  Ibs.  sulphate  of  pot- 
ash. 

No.  7.  10  Ibs.  sulphate  of  potash,  20  Ibs.  acid  phos- 
phate. 

No.  8.  10  Ibs.  nitrate  of  soda,  10  Ibs.  sulphate  of 
potash,  20  Ibs.  acid  phosphate. 

No.  9.     A  half  ton  of  stable  manure. 

No.  10.  Special.  Some  fertilizer  not  included  in  the 
above  but  used  locally  as  2  Ibs.  land  plaster  (gypsum,  or 
cow  manure,  or  sheep  manure,  etc.)  Plaster  and  manure 
show  more  marked  results  the  second  year. 

Sow  all  plats  exactly  alike  with  the  same  kind  of 
seed.  One  of  the  crops  ordinarily  raised  in  the  commun- 
ity, such  as  corn,  wheat,  barley,  etc.,  should  be  used.  If 
the  class  is  large  enough  three  or  four  set  of  plats  as  de- 
scribed above  may  be  used,  each  being  sowed  to  a  differ- 
ent crop.  When  the  crop  is  ripe,  each  plat  should  be 
separately  cut  and  threshed  and  the  yield  of  grain  and 
straw  both  carefully  weighed.  A  study  of  the  yields  of 
the  plats  as  compared  with  the  fertilizers  applied  will  give 
the  necessary  data  to  determine  what  combination  of  fer- 
tilizing material  will  cause  the  field  to  increase  its  yield 
of  that  particular  crop,  and  will  give  a  partial  check  on 
the  deficiency  of  the  soil  in  any  particular  plant  food.  A 
second  year  of  tests  on  the  same  plats  will  serve  as  a  val- 
uable check  on  the  first  year's  results. 

Let  the  students  devise  a  series  of  tests  to  show  the 
fertilizer  requirements  of  the  fruit  trees  in  some  nearby 
orchard.  Fertilizers  should  not  be  applied  around  the 
base  of  the  tree  or  much  injury  may  be  done.  The  feeding 
roots  are  spread  over  an  area  equal  to  or  greater  than  that 
covered  by  the  branches,  and  the  fertilizer  should  be 


MANUAL  OF  GENERAL  AGRICULTURE.  47 

spread  accordingly.  The  trees  should  be  numbered  and 
the  results  noted  for  two  or  three  years.  The  fertilizers 
have  little  apparent  effect  on  the  trees  for  the  first  year. 

PART  IV— AGRICULTURAL  BOTANY  AND  PLANT 
PROPAGATION. 

47.  CONDITIONS  NECESSARY  FOR  GERMINATION. 

Materials:     Six  tomato  cans,  peas,  or  beans. 

Number  the  cans  from  1  to  6.  Fill  numbers  one,  four 
and  six  with  rich,  moist,  loamy  soil.  Fill  number  three 
with  the  same  kind  of  soil,  having  first  thoroughly  air- 
dried  it.  Leave  numbers  two  and  five  without  soil.  Plant 
in  each  of  the  soil-filled  cans  six  seeds  of  peas  or  beans,  to 
a  depth  of  one  inch,  and  press  the  soil  firmly  *around  the 
seed.  Place  the  same  number  of  seed  loose  in  numbers  two 
and  five.  Number  one,  two,  four  and  six  are  to  be  kept 
moist  throughout  the  experiment.  Fill  number  five  with 
water,  that  has  been  previously  boiled  and  cooled,  to  keep 
out  air.  Place  numbers  one,  three  and  five  in  a  warm, 
light  place.  Place  number  six  in  a  warm  place,  but  cover 
it  with  dark  cloth  or  paper  to  exclude  the  light.  Keep 
number  three  in  a  refrigerator  or  ice  box  so  that  the  tem- 
perature may  be  maintained  near  the  freezing  point.  Ex- 
amine the  cans  after  two  or  three  days,  and  then  every 
day  until  you  can  answer  the  following :  Which  of  these 
conditions ;  soil,  moisture,  warmth,  air,  light,  are  neces- 
sary for  the  germination  of  se^ds?  Seeds  contain  a  very 
small  amount  of  air.  The  water  may  also  contain  a  small 
amount  of  air.  Take  this  into  account  in  answering  the 
questions. 

48.  PURITY  OF  SEEDS  AND  GERMINATION  TEST. 

(a)  Purity  of  Seeds.  Materials:  Three  samples  of 
clover  seed  or  any  small  seeds  used  locally,  chemical 
scales,  three  blotters  of  ordinary  size,  three  pans  and  glass 
to  cover  each. 

Weigh  out  5  grams  of  samples  of  seed  from  each  of 
three  samples  furnished.  Spread  this  on  a  sheet  of  paper. 


48 


MANUAL  OF  GENEEAL  AGEICULTURE. 


Separate  into  three  piles:  (1)  Chaff,  dirt,  broken  seed, 
etc.;  (2)  Sound  seed;  (3)  Weed  seed.  Weigh  each  lot. 
Save  the  seed  from  each  sample.  Record  results. 


Sample 

Weed 
seed, 
grams 

Chaff, 
dirt, 
broken 
seed, 
grams 

Per  cent 
of  sound 
seed 

Market 
price  per 
Ib. 

Actual 
cost  per 
Ib. 

1 

2 

3 

Which  gives  the  largest  amount  of  seeds  for  the  price  ? 
Does  this  sample  contain  many  weed  seeds?  Consider- 
ing price,  quality  and  weeds  seed,  which  sample  should 
be  purchased? 

(b)  Germination  Test.  Moisten  a  piece  of  blotting 
paper  and  lay  it  in  a  pan.  Take  100  seeds  from  a  sam- 
ple of  pure  seed  just  as  they  come.  Put  them  on  the  blot- 
ter and  label.  Moisten  another  piece  of  blotting  paper  and 
lay  over  them,  and  cover  with  glass  or  straw.  Keep  moist 
and  in  a  moderately  warm  room.  Do  the  same  with  the 
other  samples.  Examine  from  day  to  day,  and  remove 
the  sprouted  seeds  from  each  sample. 


Sample  No.  - 

Total 
per  cent 
germinated 

3  days 

4  days 

5  days 

1 



2 

3 

The  quickness  with  which  the  seeds  start  indicates 
something  of  their  vigor.  Which  sample  germinated 
quickest?  From  this  and  (a)  fill  out  the  following  table: 


MANUAL  OF  GENERAL  AGRICULTURE. 


40 


Sample  No. 

Market 
price  per  Ib. 

Per  cent  of 
good  seed 

Cost  per  Ib. 
of  good  seed 

1 

2 

3 

49.     PLUMP  AND  SHRUNKEN  SEEDS. 
Materials :     A  box  about  4  inches  high,  a  foot  wide 
and  2  feet  long.     Half  pint  sample  of  wheat  seed  and 
scales. 

(a)  Calculation  of  Plant  Food  in  Seeds.     Weigh  100 
plump,  well-formed  wheat  seeds.     From  this  weight  and 
the  following  data  compute  the  grams  of  nitrogen,  phos- 
phoric acid,  and  potash   per    1000   wheat   seeds.     Wheat 
contains  about  2  per  cent  nitrogen  and  90  per  cent  dry 
matter.     The  dry  matter  contains  about  2  per  cent  ash, 
about  50  per  cent  of  this  ash  being  phosphoric  acid  and 
33  per  cent  potash.     Repeat    the    experiment,  using  100 
shrunken  seeds. 

(b)  Growth  of  Plump  and  Shrunken  Seeds.     Select 
12  plump  seeds  and  also  12  that  are  shrunken.     Fill  the 
box  with  good  rich,  moist,  loamy  soil.    Plant  the  plump 
seeds  in  one  end  and  the    shrunken    seeds   in    the  other. 
Keep  the  soil  moist  and  warm.    Examine  the  young  plants 
from  time  to  time  as  they  germinate  and  grow.    Note  the 
number  of  plants  secured  from  the  plump  seeds  and  from 
the  shrunken  seeds.    Let  the  plants  continue  to  grow  for 
several  weeks. 

Questions:  Can  you  detect  any  difference  in  the 
hardiness  of  the  plants  and  the  amount  of  plant  material 
produced  by  the  two  grades  of  seed?  State  your  conclu- 
sions. 

50.     DEPTH  OF  GERMINATION. 

Materials:  Three  half-gallon  fruit  jars,  three  pint 
fruit  jars. 

(a)  Large  Seeds. — Place  about  1%  inches  of  good 
moist  soil  in  the  bottom  of  each  jar.  Plant  one  with  peas, 


50  MANUAL  OF  GENERAL  AGRICULTURE. 

one  with  beans,  one  with  corn,  as  follows:  Plant  two 
seeds  near  together  against  the  wall  of  the  jar  and  on  the 
surface  of  the  soil.  Add  an  inch  of  soil,  press  it  down 
firmly  and  after  turning  the  jar  slightly  to  one  side, 
plant  two  more  seeds  so  that  they  will  not  be  directly  over 
those  already  planted.  Continue  to  add  soil  and  plant 
seeds  every  inch  up  the  side  of  the  jar  till  near  the  top. 
Wrap  each  jar  in  dark  cloth  or  paper  to  exclude  the  light, 
and  set  in  a  warm  place.  From  day  to  day,  remove  the 
wrapping  from  the  jars  and  note  the  growth,  recovering 
them  immediately.  This  exercise  should  give  some  idea 
of  the  power  of  different  kinds  of  seeds  to  force  their 
plantlets  up  through  the  soil.  Note  the  depth  of  the  low- 
est seed  in  the  jars  that  is  able  to  penetrate  to  the  surface. 

(b)  Small  Seeds. — Eepeat  (a)  using  the  pint  jars 
and  planting  the  lowest  seeds  about  an  inch  from  the  bot- 
toms. Use  small  seeds,  such  as  radish,  alfalfa,  clover. 

How  do  the  depths  of  germination  with  large  seeds 
and  small  compare?  Give  reason  for  this.  Oil  producing 
seeds  contain  much  more  food  in  proportion  to  their  size 
than  do  the  starchy  seeds. 

51.     OSMOSIS. 

Materials:  Potato,  two  wide  mouth  glasses  or  beak- 
ers, glass  tube  6  inches  long  and  about  3-16  inch  inside 
diameter,  egg,  hatpin,  sealing  wax,  salt. 

1.  Pare  a  potato  and  cut  slices  from  it.    Place  some 
of  these  in  water  and  some  in  a  strong  solution  of  salt 
made  by  placing  a  small  handful  of  salt  into  a  glass  of 
water.    Examine  at  the  next  exercise. 

2.  Cement  with  sealing  wax  to  the  smaller  end  of  an 
egg  a  piece  of  glass  tubing  about  6  inches  long  and  about 
3-16  inch  inside  diameter.     Clip  away  part  of  the  shell 
from  the  larger  end  of  the  egg,  place  in  a  wide  mouth  bot- 
tle or  small  beaker  full  of  water  and  then  carefully  pierce 
a  hole  through  the  upper  end  of  the  eggshell  by  pushing 
a  hatpin  through  the    glass   tube.    Examine  at   the  next 
exercise. 


MANUAL  OF  GENERAL  AGEICULTURE.  51 

In  the  case  of  the  potato  the  piece  in  water  is  plump 
and  rigid,  which  shows  that  the  water  passed  into  the 
potato  faster  than  the  sap  passed  out.  The  piece  in  the 
salt  solution  is  wilted,  which  shows  that  the  salt  solution 
did  not  pass  into  the  potato  as  fast  as  the  sap  passed  out. 

In  the  case  of  the  egg,  the  water  passed  into  the 
egg  more  readily  than  the  denser  egg  solution  passed  out 
into  the  water.  As  the  water  passed  in,  the  egg  albumen 
was  pushed  up  the  tube  by  osmosis.  Whenever  a  plant  or 
an  animal  membrane  separates  two  solutions,  there  is  an 
interchange  of  the  two.  The  less  dense  the  solution,  the 
more  rapidly  the  water  passes  through  the  membrane.  The 
solutions  of  root-hairs  are  more  dense  than  the  soil  solu- 
tions, hence  more  water  passes  into  the  root  than  passes 
out  into  the  soil. 

Questions:  I.  What  is  the  danger  in  using  an  ex- 
tremely strong  fertilizer?  2.  How  does  this  experiment 
show  that  an  excess  of  alkali  in  the  soil  often  prevents 
the  growth  of  the  plant? 

52.     THE  WORK  OF  LEAVES. 

Materials:  Two  small  watch  glasses,  vaseline,  two 
circular  disks  of  two  pins. 

1.  Transpiration.     Fasten  two  small  watch  glasses, 
one  on  each  side  of  a  leaf  of  a  plant  growing  vigorously 
out  of  doors.    The  glasses  may  be  held  in  place  by  sealing 
the  margin  of  each  all   the   way   around   by   vaseline  or 
grafting  wax.    An  hour  later  or  at  the  next  meeting  exam- 
ine the  drops  of  water  inside  of  each  glass.     The  giving 
off  of  moisture  by  the  leaves  is  called  transpiration. 

2.  Light.    Select  some  leaves  on  a  vigorously  grow- 
ing plant.    Shut  off  the  sunlight  from  parts  of  the  selected 
leaves,  which  must  be  left  on  the  plant  and  as  little  injured 
as  possible,  by  pinning  circular  disks  of  cork  loosely  on 
opposite  sides  of  each  leaf.  Two  or  three  days  later  remove 
these  leaves  and  the  cork  disks.    Compare  the  color  of  the 
covered  area  with  the  color  of  the  remainder  of  the  leaf 
and  explain.     Why  do  most  plants  not  do  well  in  the 
shade  of  trees? 


52  MANUAL  OF  GENERAL  AGRICULTURE. 

3.  Oxygen  Making.  Place  some  green  aquatic  plant 
in  a  glass  jar  full  of  water  in  front  of  a  sunny  window  at 
about  70°  F.  In  a  short  time  note  the  formation  of  oxy- 
gen bubbles  looking  silvery  by  reflected  light.  Remove  to 
a  dark  place  and  after  a  few  minutes  examine  by  lamp 
light  to  see  whether  the  rise  of  the  bubbles  still  continues. 

One  of  the  most  important  facts  about  life  is  the 
taking  in  by  plants  from  the  air  of  carbon  dioxid,  a  com- 
pound composed  of  carbon  and  oxygen.  The  plants  use 
the  carbon  and  give  off  the  oxygen.  The  process  is  the 
opposite  in  the  case  of  animals,  which  breathe  off  car- 
bon dioxid  and  breathe  in  oxygen.  Plants  by  a  dusty 
road  side  often  become  covered  with  dust.  What  effect 
would  this  have  on  1,  2  and  3? 

53.     STUDY   OF   THE   CHARACTERS   OF   BARLEY.* 

Materials  for  this  exercise  and  also  for  exercises  54 
and  55  may  be  obtained  from  the  University  of  Nebraska, 
Department  of  Field  Crops,  Lincoln,  Neb.  For  Exercise 
53,  Order  Lot  3.  This  lot  contains  nine  barley  types  with 
about  25  specimens  per  type.  Price  per  lot  $1.75.  For 
Exercise  54,  Order  Lot  58.  This  lot  contains  fourteen  spe- 
cies of  cultivated  grasses  given  in  the  exercise,  together 
with  one  additional.  Price  per  lot  $1.75.  For  Exercise  55 
(a)  Order  Lot  59.  This  lot  contains  the  seeds  of  eleven 
species  of  clovers  given  in  the  exercise  with  two  addi- 
tional. Price  per  lot  in  2-ounce  bottles  $1.50.  For  55  (b) 
Order  Lot  58,  which  contains  the  seeds  of  the  fourteen  spe- 
cies of  cultivated  grasses  given  in  the  exercise  with  one 
additional.  Price  per  lot  in  2-ounce  bottles  $1.25.  One  or 
more  lots  may  be  ordered,  but  the  lots  will  not  be  broken. 

Cultivated  barleys  include  a  number  of  types,  or 
races,  and  may  be  classified  as  follows: 

(1)  Two-rowed  barley Hordeum  sativum  distichon 

(2)  Six-rowed  barley Hordeum  sativum  hexastichon 

*     The  two-rowed  barleys  commonly  grown  are  charac- 
terized by  their  large,  plump  grain.    In  Europe  these  bar- 

*For  exercises  similar  to  this  on  corn,  wheat  and  oats  see 
' '  Examining  and  Grading  Grains ' '  by  Lyon  and  Montgomery. 


MANUAL  OF  GENERAL  AGRICULTURE. 


53 


leys  are  used  almost  exclusively  for  malting,  and  hence 
the  name  "malting  barleys"  has    come    to    be  generally 


FIG.  1. 


Types  of  barley  spikes:   A,  two-rowed  brewing  barley;   B, 
six-rowed  hulless  barley 


applied  to  them.    However,  in  America  the  six-rowed  bar- 
leys are  generally  used  for  this  purpose. 

The  six-rowed  barleys  include  the  ' '  naked, "  or  *  *  hull- 
less"  varieties,  as  well  as  most  of  our  common  cultivated 
barleys.  The  six-rowed  barleys  are  generally  more  pro- 
lific than  the  two-rowed,  and  are  most  generally  grown  in 
this  country.  The  grains  of  six-rowed  barleys  are  smaller 


54  MANUAL  OF  GENERAL  AGRICULTURE. 

and  not  so  plump  as  those  of  the  two-rowed  barleys,  but 
are  higher  in  nitrogen. 

The  varieties  of  barley  are  numerous,  but  only  a  com- 
paratively few  are  grown  in  the  United  States. 

Carefully  examine  samples  of  each  of  the  above  types 
of  barley  including  samples  of  both  black  and  white  hull- 
less  barley. 

Make  drawings  from  a  spike  of  each  type,  showing 
the  imbricated  view. 

Note  that  the  berry  of  ordinary  barley  is  tightly  in- 
closed by  the  flowering  glume,  called  the  "hull,"  while 
in  hulless  barleys  the  flowering  glume  and  palet  do  not 
adhere  closely  and  the  berry  is  free. 

In  this  respect  hulled  barley  is  similar  to  oats,  and 
hulless  to  wheat. 

LABORATORY  STUDY  OF  CHARACTERS. 

Typical  samples  in  the  spike  and  of  the  threshed 
grain  are  provided.  Carefully  describe  both  the  spike  and 
grain  of  one  or  more  samples  of  the  principal  types  of  bar- 
ley, as  the  two-,  four-,  and  six-rowed  barleys,  and  black 
and  white  hulless  barleys. 

The  characteristics  are  obvious  enough,  so  that  with 
a  little  careful  comparison  there  should  be  no  trouble  in 
finding  the  proper  adjective  in  the  descriptive  list. 

Use  the  outline  for  describing  barleys,  filling  it  out 
carefully. 

TERMS  FOR  DESCRIBING  BARLEYS. 

Spike 

'Two-rowed  (Fig.  1,  A).    }  This  refers  to  the  number  of  rows 

Six-rowed  (Fig.  1,  B).     /      of  grain  on  the  spike. 

Awned  (Fig.  1,  A). 

Partly  awned  (Fig.  1,  B). 

Awn  less. 
Length  (inches). 

[  Open  (Fig.  1,  A).  1  Has  reference  to  how  close  or  far 

\  Compact  (Fig.  1,  B).  apart  the  spikelets  are  on   the 

I  Crowded.  rachis. 


MANUAL  OF  GENEEAL  AGEICULTUEE.  55 

Shape 

'  Tapering  toward  tip.       When  upper  spikelets  are  appressed. 
]  When  spikelets  at  both  base  and 
Tapering  both  ways.      >      tip    are    more    appressed    than 

J      those  at  middle. 
Uniform  (Fig.  1,  A). 
Tip  tapering  (Fig.  1,A).    \  When  terminal  spikelets  are  not 

/      well  filled  out. 

Tip  blunt  (Fig.  1,  £).          Terminal  spikelets  well  filled  out. 
Base  abrupt.  Basal  spikelets  well  filled  out. 


Base  tapering.  Basal  spikelets  not  well  filled  out. 

Sterile  spikelets,  1,  2,  3,  etg, 


Color 

<  Whitish. 

Yellowish. 

Yellowish  brown. 

Brown. 
.  Black. 

Awns 

Long  (length  5  inches  or  more). 


1. 

2. 


Medium  (length  3  to  5  inches). 

Short  (length  less  than  3  inches). 

Parallel  (tig.  1,  B).  }  Refers  to  the  relative  position 

Spreading  (big.  1,  A).  j      of  the  awns  to  the  head. 

This  refers  to  the  dropping  of 


(  Deciduous. 

\  Partly  deciduous  (Fig.  1,  B). 

(  Persistent  (fig.  1,  A). 


the  awns  at  maturity.  The 
awns  all  drop  off  on  some 
varieties,  while  on  others 


they  are  very  persistent. 
Color 

Whitish. 
Yellowish. 


1. 


Brownish. 
Black. 


Spikelet 

(This  is  not  a  spikelet  in  the  botanical  sense,  but  really  a  mesh  of 
three  spikelets.) 

1 .  Number  grains  per  spikelet  (1,  2,  3). 

2.  Number  of  sterile  flowers.     (Refers  to  sterile  flowers  in  a 
spikelet.) 

Size 

(  Broad  (Fig.  2,  C).        )  This  depends  largely  on  the  shape 
1.  \  Medium  (Fig.  2,  B).  of  the  grain    and  how  well  it  is 

{  Narrow  (Fig.  2,  A).     J       developed. 
Outer  Glume.    (In  barleys  these  are  very  narrow  and  pointed.) 

f  Awned  (Fig.  2,  B}.       }  The  outer  or  empty  glume  should 
1.  \  Awn-pointed.  \      not  be  confused  with  the  flower- 

(  Awnless  (Fig.  2,  D).    J      ing  or  seed-bearing  glume. 


56 


MANUAL  OF  GENERAL  AGRICULTURE. 


Grain 


}  This  is  the  distinguishing  characteristic 

Inclosed  in  flower-    I       between  the  naked  or  hulless  barley 

ing  glume.  [      and  the  ordinary  kind.    In  the  latter 

Free  (naked).  the  grain  is  so  tightly  inclosed  that 

J       it  is  not  freed  in  threshing. 


FIG.  2.  Types  of  barley  spikelets:  A,  spikelet  from  two-rowed 
barley;  B,  spikelet  from  six-rowed  barley;  C,  a  six-rowed  hulless 
barley;  D,  a  white  hulless  and  awn  less  barley;  E  shows  a  barley 
spikelet  torn  apart. 

{Hard.  }  This  point  is  most  easily  determined  by  biting  or 
Medium.  )•  cutting  the  grains  and  comparing  with  stand- 
Soft.  J  ard  samples. 

Shape 

}  Different  varieties  of  barley  show  considerable 
Long.  variation  in  size  and  ratio  of  length  to  diam- 

Medium.  }•      eter.     Pick  out  about  six  typical  grains  to 
I  Short.       J       examine  for  these  points. 

Thin. 

\  Medium. 
[  Plump. 


MANUAL  OF  GENERAL  AGEICULTURE. 


57 


Crease 

Deep. 

Medium. 

Full. 
Cross  section 

(  Horny. 
1.  \  Dull. 
(  Starchy. 


Color 


Black. 

Purple. 

Purplish. 

Brown. 

Yellowish. 

Whitish. 


Cut  cross  sections  of  several  typical  grains. 


This  point  is  determined  by  making  cross  sec- 
tions and  examining  carefully.  Where  only 
part  of  the  grains  show  one  characteristic 
and  tfie  rest  some  other,  the  per  cent  of  each 
kind  should  be  expressed. 


When  black  hulless  barleys  are  fully  matured 
they  are  purplish  black  in  color,  but  when 
cut  very  green  they  are  ofcen  a  yellowish 
white  in  color,  with  only  a  tinge  of  purple. 


Weight  of  100  grains grams 

OUTLINE  FOR  DESCRIBING  BARLEYS. 
Spike 

1  

2 

3 

4 

Shape 

I... 

2 

3 

4 

Color 

1 

Awns 

1 

2 

3 

Color 

1 

Spikelet 

1 

2 

Size 

I 

Outer  Glume 

I... 


58  MANUAL  OF  GENERAL  AGRICULTURE. 

Grain 

1 

2 

Shape 

1 

2 

Crease 

1 

Cross  section 

1 

Color 

1 

Weight  of  100  grains  (grams) 

Question:  What  advantage  has  hulless  barley?  Hull 
barley  ? 

54.     OUTLINE  FOR  DESCRIBING  GRASSES. 

Materials:    Lens.    See  Exercise  53. 

The  following  outline  is  used  in  the  study  of  common 
cultivated  grasses.  By  following  the  outline  one's  at- 
tention is  called  to  the  distinguishing  characteristics  of 
each  kind,  giving  not  only  a  means  of  identification  but 
a  good  knowledge  of  the  grass. 

The  stem  and  leaves 

Height    

Color    of    stem 

Color  of  leaves 

Number  of  leaves 

Head 

Awned    or    awnless 

Panicled,  compact,  or  spiked 

Size  (give  length  and  diameter) 

Color   of   awns 

Color  of   chaff 

Soot 

Does    it    spread    from    rootstocks? 

Is  it  a  sod-forming  or  bunch  grass? 

Seeds 

Size    (give    average    length    in    inches) 

Color    (general    color) 

General  Notes 

Is  seed  free  or  inclosed  in  scales! 

Weight    per   bushel 

Amount   sown   per   acre 

Vitality    


MANUAL  OF  GENERAL  AGRICULTURE.  59 

Drawings  of  Seeds.  Make  drawing  from  convex  side. 
Make  drawing  of  cross  section. 

Question :  Give  an  illustration  of  a  sod  forming  grass 
and  a  bunch  forming  grass.  Discuss  the  advantage  of 
each. 

55.     IDENTIFICATION  OF  CLOVER  AND  GRASS 
SEEDS. 

Materials:    Lens.    See  Exercise  53. 

There  is  no  work  which  requires  more  careful  atten- 
tion or  is  more  valuable  than  the  identification  of  grass 
and  clover  seeds,  and  separating  them  from  their  adul- 
terants. 

For  examining  the  seeds  a  small  lens  is  very  use- 
ful. Use  the  following  artificial  key,  which  is  not  in- 
tended to  describe  the  seed  but  simply  calls  attention  to 
the  most  prominent  characteristics  of  each  variety.  It 
is  much  better  to  first  learn  to  identify  by  use  of  the 
key  than  by  use  of  the  drawings. 

(a)   Key  for  Identification  of  Clover  Seeds 

Seed  free    (not  inclosed  in  pod) 
Seed  bean-shaped 

Color,  pinkish,  %  in.  long Crimson  Clover 

Color,   mostly  yellow;    large   seeds   are   kidney  shaped Alfalfa 

(Turkestan  alfalfa  is  same,  but  slate  colored.) 

Seeds  larger  and  more  regular  than  in  alfalfa Burr  Clover 

Color,  dark  yellow  to  brown Yellow   Trefoil 

Seed  oval-oblong 

Color,   yellow;    seed   notched   near   one   end Bokhara   Clover 

Seed  heart-shaped 

Color,   yellow   to   brown White    Clover 

Color,  dark  green  to  black Alsike  Clover 

Seed  somewhat  triangular 

Color,  yellow  to  brownish Red  Clover 

Seed  inclosed  in  pod 

Pod  large  and  corrugated,  ^4  in-  l°ng 

Color,   brown;    seed,   bean-shaped Sainfoin 

Pod  whitish,  %  in.  long 

Color,  yellow;   seed  oval,  notched  near  end 

Yellow  Sweet  Clover 
Pod  brown,  i/8  in.  long 

Color,   dark  brown,   seed  mottled Japan   Clover 


60  MANUAL  OF  GENEEAL  AGEICULTUEE. 

(&)  Key  for  Identification  of  Grass  Seeds 
Seeds  distinctly  awned 

Seed  }4   in.  or  more  in  length 

Very  hairy  or  pubescent,  flat,  thin Meadow  Foxtail 

Awns  attached  at  tip Annual  Eye  Grass 

Awns  long,  twisted,  attached  near  base... .Tall  Meadow  Oat  Grass 
Seeds  less  than   y±   in.  long 

Small   brownish   seed Sheep    Fescue 

Short-awned   or   awn-pointed 

Small,  dark  brown  seeds,  very  rough  near  tip.. ..Crested  Dog's-Tail 

%    in.    long,    smooth,    light    colored Wheat    Grass 

i/4    in.   or  less  in   length Orchard   Grass 

Awnless 

%  in.  long  or  thereabout,  nerves  very  prominent. ...Brome  Grass 
About  i/i  in.  long  (  Note  difference  in  shape  I  -Perennial   Eye   Grass 

light  brown 1       and  size  of  rachilla       f Meadow  Fescue 

Hard,  smooth  seeds,  about  l/±   in.  long 

Dark  brown   color Johnson   Grass 

%  in.  long  or  less 

Keel  rough,   sawlike Eedtop 

Keel  not  commonly  rough Kentucky  Blue  Grass 

Seed  free  from  glumes,  polished 

Very  small,  1-32  in.  in  length,  polished Timothy 

56.     CUTTINGS  AND  THEIR  USE  IN  PROPAGATION. 

The  more  common  forms  of  artificial  reproduction  are 
by  cuttings,  grafting  and  budding.  A  cutting  is  a  de- 
tached portion  of  a  plant  inserted  in  soil  (or  in  water) 
for  the  purpose  of  producing  a  new  plant.  Cuttings  may 
be  divided  into  three  classes :  1.  Hard-wood  cuttings.  2. 
Soft-wood  cuttings  (herbaceous).  3.  Root-cuttings. 

1.  Hard  Wood  Cuttings.    A  hard-wood  cutting  is  a 
cutting  from  the  ripened  wood  of  a  deciduous  plant  of  the 
present    or    previous    season's    growth.     The    cultivated 
plants  most  commonly  propagated    by    the  use  of    hard- 
wood cuttings  are  grape,  olive,  fig,  quince,  currant  and 
gooseberry,  and  many  ornamental  shrubs,  such  as  privet, 
tamarisk,  hydrangra,  etc. 

2.  Soft  Wood  Cuttings.    This  class  of  cuttings  is  ex- 
amplified  in  the  ''slips"  used  to  increase  the  number  of 
roses,  carnations,  geraniums,  fuchsias,  begonias,  etc.    Leaf 
cuttings  are  often  employed  in  multiplying  begonias,  cacti 
and  other  plants  having  thick  fleshy  leaves  containing  a 


MANUAL  OF  GENERAL  AGRICULTURE.        61 

large  quantity  of  plant  food.  Soft-wood  cuttings  are  of 
little  importance  in  agriculture. 

3.  Root  Cuttings.  Short  cuttings  of  roots  may  be 
used  in  the  propagation  of  many  plants,  notably  the  horse 
radish.  The  roots  of  lippia,  bermuda  grass  and  some  other 
grasses  can  be  cut  into  short  pieces  and  planted. 

Obtain  some  hard-wood  cuttings  of  apple,  peach,  pear, 
plum,  berry  canes,  fig,  olive,  quince  and  any  others  that 
are  available.  Get  cuttings  about  18  inches  long  and  3-8 
to  5-8  inch  in  diameter,  using  wood  of  the  previous  sea- 
son's growth.  They  should  be  obtained  during  the  dor- 
mant period  (January)  or  at  the  time  of  pruning.  Cut 
five  from  each  tree  and  tie  them  in  separate  bundles  with 
the  butts  all  one  way,  then  label  with  a  piece  of  wood. 

In  order  to  save  time  and  trouble  we  may  as  well  ob- 
tain scions  for  grafting  at  this  time  and  care  for  them  in 
the  same  ways  as  described  below  for  cuttings.  A  scion 
is  a  portion  cut  from  a  plant  to  be  inserted  upon  another 
plant  with  the  intention  that  it  shall  grow.  Obtain  scions 
to  be  grafted  on  year  old  seedlings  grown  as  indicated  in 
Exercise  56.  If  there  are  no  year  old  seedlings  to  be 
grafted,  no  scions  need  be  gathered,  but  in  order  to  save 
time  in  getting  started  seedlings  should  be  bought.  Select 
10  scions  of  about  the  size  of  the  seedlings  to  be  grafted 
so  that  they  may  be  easily  matched,  tie  in  bundles  and 
label  with  a  piece  of  wood.  Heal  in  the  cuttings  (and 
scions)  by  digging  a  trench  in  moist,  sandy,  well  drained 
soil  in  a  shady  place  as  on  the  north  side  of  a  building. 
Place  the  bundles  in  the  trench  in  a  slightly  inclined  posi- 
tion and  cover  all  over  but  the  tips,  pressing  the  soil 
firmly  about  them. 

In  February  or  March,  when  the  nursery  is  ready, 
dig  up  the  cuttings  and  plant  in  nursery  rows,  making  the 
rows  2  feet  apart  for  hand  cultivation  or  3  feet  apart  for 
horse  cultivation  and  plant  the  cuttings  8  inches  apart  in 
the  rows. 

Only  berries,  fig,  olive  and  quince  are  raised  by  cut- 
tings, but  for  the  sake  of  experiment  and  practice  try  cut- 
tings of  the  others. 


62  MANUAL  OF  GENEBAL  AGBICULTURT1. 

57.     ESTABLISHING  A  DECIDUOUS  ORCHARD. 

The  operations  involved  in  the  establishment  of  a  de- 
ciduous orchard  are  as  follows : 

1.  Collection    of    Seed.     When  seeds  are  to  be  col- 
lected on  a  large  scale  it  is  usual  to  get  them  from  some 
cannery,  but  when  only  a  few  are  desired  they  may  be 
obtained  in  any  convenient  manner.     As    seeds    planted 
seldom  come  true  to  types,  all  plantings  of  seed  must  be 
made  with  the  knowledge  of  the  kind  of  scions  that  are 
to  be  grafted  or  buds  to  be    budded  on   the  young  seed- 
lings.   For  instance,  it  is  customary  to  make  combinations 
about  as  follows :    Peach  budded  on  peach,  preferably  on 
strong  growing  yellow  peach  seedling.     Pear,  budded   or 
grafted    on    pear,    preferably    on    Keiffer    pear.     Apple 
grafted  on  apple.     By   root    grafting    onto  roots  of    the 
Northern  Spy  apple,  trees  obtained  are  said  to  be  immune 
from  attacks  of  the  Woolly  Aphis.    Plum  or  prune  budded 
on  peach  in  moist,  sandy   loam    soils.     Plum   budded  on 
Myrobolan  when  subject  to  overflow,  standing  water,  or 
on  heavy  soil.     Apricot,  same  as  plum.     Walnut  grafted 
on  California    black    walnut.     Quince,  olive    and    fig  are 
grown  from  cuttings. 

After  the  seeds  are  collected  keep  them  in  a  cool  dry 
place,  but  not  in  an  air-tight  receptacle.  Obtain  at  least 
five  seeds  of  each  fruit  to  be  propagated  and  ten  of  the 
smaller  kinds  as  they  are  more  likely  to  be  lost. 

2.  Stratification  of  Seed.     In  January  obtain  some 
cheesecloth  and  cut  into    squares    of   about  a    foot  em-'!. 
making  twice  as  many  squares  as  you  have  sets  of  seeds. 
Moisten  all  the  cloths  with  water.     Take  the  seeds  pre- 
viously collected  and  select  a  spot  in  the  garden,  prefer- 
ably one  in  sandy  soil.    Dig  a  hole  a  foot  square  and  a  foot 
deep.    In  the  bottom  spread  out  one  of  the  cloths  and  place 
on  it  any  set  of  seeds;  then  over  them  place  another  cloth 
and  two  inches  of  soil.     Place  another  cloth,  seeds,  cloth, 
and  soil,  in  the  same  way  until   all   the   seeds  have  been 
stratified.     Record  in  your  note  book  the  various  strata. 
Of  course  if  there  are  more  than  five  sets  of  seeds  to  be 
stratified  the  hole  must  be  deeper  than  a  foot  or  prefera- 


MANUAL  OF  GENEEAL  AGEICULTUEE.  63 

bly,  dig  two  holes  rather  than  go  beyond  a  foot  deep. 
Place  a  stake  by  the  seeds  with  your  name  on  it  so  that 
they  may  be  readily  located.  Allow  the  seeds  to  remain  in 
the  ground  about  six  weeks. 

3.  Transplanting  to  the  Nursery.    The  best  location 
for  a  nursery  is  on  loam  or  sandy  soil,  but  trees  may  be 
successfully  grown  in  less  favorable  soil.    The  land  should 
be  plowed  deep  and  thoroughly  cultivated.    By  the  use  of 
string  and  stakes    dig   with  a    hoe  a   trench   the  desired 
length.     No  definite  depth  can  be  given  for  planting  the 
seeds,  but  the  smaller  ones  such  as  pear  or  apple  should 
be  planted  one  and  one-half  inches  deep,  while  the  larger 
ones  like  the  peach  or  apricot  two  inches  deep. 

Carefully  dig  up  the  stratified  seeds  and  take  them 
to  the  nursery  taking  care  not  to  injure  the  young  sprouts. 
Plant  them  in  rows  about  six  to  eight  inches  apart.  The 
rows  should  be  about  three  and  one-half  feet  apart  for 
horse  cultivation,  but  for  hand  cultivation  two  feet  is  suf- 
ficient. Plant  only  the  sprouted  seeds.  Mark  with  stakes 
the  location  of  each  set  of  seeds.  The  stakes  should  be 
uniform  in  size  and,  if  desired,  painted  white.  A  con- 
venient size  for  stakes  is  1x2x24  inches. 

4.  Stripping  the  Young  Seedlings.    By  the  following 
summer  it  will  be  found   that    the    small   branches  have 
grown  down  close  to  the  ground.     In  order  to  facilitate 
the  operation  of  either  budding  or  grafting  it  is  necessary 
to  break  off  with  the  fingers  the  young  limbs  close  to  the 
ground  and  up  to  a  distance  of  five  or  six  inches,  accord- 
ing to  the  size  of  the  tree.    Nothing  else  need  be  done  to 
the  trees  the  first  summer,  but  of  course  the  ground  should 
be  well  cultivated,  weeds  kept  down  and  irrigation  prac- 
ticed according  to  local  conditions. 

5.  Grafting  and  Budding.    Grafting.    Where  graft- 
ing is  to  be  done  the  scions  of  the  desired  varieties  should 
be  secured  when  the  trees    are    pruned  in    December  or 
January.    Care  for  the  scions  and  insert  them  as  described 
in    Exercise    56.     Budding.     What    is    commonly    called 
"June  Budding"  is    usually    practiced  in    California  in 
April  or  May.    The  bud  is  inserted  close  to  the  ground  in 


64 


MANUAL  OF  GENERAL  AGRICULTURE 


either  of  these  months.  In  selecting  the  bud  go  to  some 
tree  that  produces  the  desired  variety  of  fruit  and  cut  off 
a  few  vigorous  growing  limbs.  Carry  limbs  and  all  to  the 
nursery  and  then  cut  and  insert  buds  as  described  in  Ex- 
ercise 59. 

6.  Heading   Back   to   the   Bud.     After  the  bud  has 
grown  into  a  branch  from  four  to  six  inches  long,  head 
back  to  the  bud  by  cutting  with  a  sharp  knife  the  main 
stock  completely  off  just  above  the  bud.  (Fig.  lie). 

7.  Digging  the  Nursery  Trees.    The  following  Feb- 
ruary the  trees  will  be  about  two  years  old  from  the  seed, 
but  the  age  of  a  tree  is  not   reckoned   from    the  time  of 

planting  the  seed,  but  from  the  time  of 
inserting  the  bud  or  graft.  Our  trees  are 
therefore  considered  as  one  year  old. 
(Large  nurserymen  often  obtain  one  year 
old  seedlings  from  France  at  a  low  cost, 
thus  saving  a  year's  time.) 

In  February  dig  the  trees  from  the  nur- 
sery rows  so  as  to  obtain  a  large  number 
of  small  branching  roots.  (Previous  to 
digging,  the  orchard  should  be  made, 
ready  to>eceive  the  young  trees  as  de- 
scribed in  Exercise  60.)  In  lifting 
from  the  nursery,  digging  with  a  well- 
sharpened  spade,  which  will  sever  the 
long  roots  cleanly,  is  perhaps  the  best 
method.  The  tap  root  cuts  no  figure  in 
California  orchard  planting,  but  it  is  im- 
portant to  have  as  many  small  lateral 
roots  as  possible.  Any  broken  roots 
should  be  clipped  off.  Do  not  permit  the 
roots  after  lifting,  to  dry  out.  Cover  them  with  wet  sacks 
or  wet  straw  unless  they  are  to  be  planted  immediately. 
If  trees  after  digging  are  not  to  be  planted  the  same 
day  they  may  be  kept  by  being  "healed  in."  To  heal  in, 
dig  a  trench  in  light,  moist,  but  well  drained  soil ;  put  the 
trees  in  singly,  side  by  side,  laying  the  tops  all  one  way, 
then  shovel  the  earth  over  the  roots  until  they  are  well 


Fig.  3. 


MANUAL  OF  GENERAL  AGRICULTURE.  G5 

covered  with  loose  soil.     Be  sure  the  soil  sifts  down  well 
between  the  roots. 

This  is  the  way  to  care  for  trees  received  from  any 
nursery  if  they  are  not  to  be  planted  at  once.  In  remov- 
ing from  the  trenches  be  sure  the  roots  do  not  dry  out. 
Directions  for  planting  are  given  in  Exercise  61.  The 
trees  should  be  cut  back  to  18  inches  just  before  planting 
as  shown  in  figure  3. 

58.     GRAFTING. 

Materials:  Grafting  knife  or  medium  large  pocket 
knife  with  sharp  blade,  saw,  thin  chisel  or  grafting  tool 
(Fig.  5)  or  screw  driver,  2  quart  pail,  round  paint  brush 
about  three-fourths  inches  in  diameter,  grafting  wax  pre- 
pared as  follows:  In  the  pail  place  one  pound  of  resin, 
one  pound  of  beeswax  and  one-half  pound  of  rendered 
tallow  (obtained  by  melting  beef  tallow  and  allowing  it 
to  cool.)  Thoroughly  melt,  stirring  occasionally  with  the 
brush.  iWaxed  string.  Before  removing  the  melted  graft- 
ing wax  from  the  fire  place  into  it  a  ball  of  No.  18  knit- 
ting cotton.  Leave  it  in  the  wax  for  several  minutes, 
turning  frequently.  Remove  from  the  pail  and  allow  to 
drain  and  dry. 

Were  all  forms  of  the  art  of  grafting  to  be  taken  from 
the  horticulturist  today,  commercial  fruit  growing  in  its 
high  state  of  perfection  would  decay  with  the  orchards 
now  standing.  All  the  common  pomaceous  fruits  (apples 
and  pears),  the  stone  fruits  (peaches,  plums,  cherries  and 
apricots),  and  citrus  fruits  (lemons  and  oranges),  are  now 
multiplied  by  grafting  and  budding.  The  progress  in 
plant  breeding  and  the  great  rapidity  which  new  sorts 
are  now  distributed  could  not  be  obtained  without  the  aid 
of  budding  or  grafting.  Under  the  existing  conditions  it 
is  not  necessary  for  the  originator  of  a  new  sort  of  apple 
to  give  any  thought  to  the  question  of  fixing  that  type  so 
it  may  be  reproduced  by  seed.  Grafting  and  budding  has 
settled  that  long  ago. 

(a)  Whip  Grafting.  This  style  of  grafting  is  the 
one  most  universally  used.  It  has  the  advantage  of  being 


66 


MANUAL  OF  GENEEAL  AGEICULTUEK 


well  adapted  to  small  plants  only  one  or  two  years  old. 
Also  it  may  be  used  on  seedlings  standing  in  the  nursery 
or  on  seedlings  or  roots  dug  up  and  the  work  done  on  a 
bench. 

1.  Grafting  Seedlings  in  the  Nursery.  The  stock  is 
the  plant  or  part  of  it  upon  which  the  bud  or  scion  is  in- 
serted, in  this  case  the  seedling  trees.  Make  the  graft  by 
cutting  the  stock  off  di- 
agonally just  above  the 
ground.  Make  one  long 
smooth  cut  with  a  sharp 
knife,  leaving  about 
three-fourths  of  an  inch 
of  cut  surface  as  shown 
in  figure  4,  a.  Place 
the  knife  about  one- 
third  of  the  distance 
from  the  end  of  the  cut 
surface,  at  right, angles 
to  the  cut,  and  split  the 
stock  in  the  direction  of 
its  long  axis.  Cut  the 
scion  with  about  three 
buds,  then  cut  the  lower 
end  as  shown  in  figure 
4,  b,  so  that  when  the 
stock  and  scion  are 
forced  together  as 
shown  in  figure  4,  c,  the  cut  surface  will  fit  neatly  together 
and  one  will  nearly  cover  the  other  if  the  stock  and  scion 
are  of  the  same  size.  The  importance  of  having  an  inti- 
mate connection  between  the  growing  tissues  (the  cam- 
bium layers)  of  both  stock  and  scion,  cannot  be  too 
strongly  emphasized,  for  upon  this  the  success  of  grafting 
depends.  A  difference  in  diameter  of  the  two  parts  to  be 
united  may  be  adjusted  by  placing  the  scion  so  that  the 
cambium  layers  meet  on  one  side  only,  but  it  is  desirable 
to  have  stock  and  scion  nearly  the  same  size  if  possible. 


FIG.  4. — Whip  grafting ;  a,  the  stock; 
b,  the  scion;  c,  stock  and  scion  united. 


MANUAL  OF  GENERAL  AGRICULTURE. 


67 


After  the  parts  have  been  forced  together,  tie  them  with 
waxed  string,  then  coat  with  grafting  wax. 

2.  Grafting  Seedlings  not  in  the  Nursery.  Root 
Grafting.  This  is  the  prevailing  Eastern  method  and  is 
not  so  much  in  use  in  California  except  for  root  grafts  on 
Northern  Spy  apple  stock.  Cut  the  scion  with  about  three 
buds  as  before  and  cut  the  stock  about  as  long  as  the  scion. 
If  the  roots  are  to  be  used  cut  them  into  lengths  of  about 
five  or  six  inches. 

The  stock  and  scions  are  obtained  in  the  fall  or  in 
December  and  stored  until  February  or  March,  when 
grafting  can  be  done.  They  may  be  packed  away  in  moss, 
sawdust,  or  in  sand  or  healed  in,  in  the  usual  way.  (See 
Ex.  56.)  In  the  spring  when  setting  out  in  the  nursery,  set 
the  root  graft  just  below  the  surface  of  the  ground  and 
the  seedling  graft  just  above  the  surface. 

Cleft  Grafting.  This  style  of  graft  is  particularly 
adapted  to  large  trees  when  for  any  reason  it  becomes 
necessary  to  change  the  variety.  Branches  too  large  to 
be  worked  by  other  methods  can  be  cleft  grafted.  Saw  off 
a  branch  to  be  grafted,  being  careful  not  to  loosen  the  bark 
from  the  portion  of  the 
stub.  Split  the  exposed 
end  with  a  broad,  thin 
chisel  or  grafting  tool 
or  hatchet,  (fig.  5). 
Then  with  the  wedge- 
shaped  prong  at  the  end 
of  the  grafting  tool  or 
with  a  hatchet  or  even 
a  screw  driver,  spread 
the  cleft  so  that  the 
scions  (fig.  6,  a)  may  be 
inserted  (fig.  6,  b.)  The 
scion  should  be  of  the 
previous  season's 
growth  and  should  be  long  enough  to  have  two  or  three 


FIG.    5. — Grafting    tool. 


68 


MANUAL  OF  GENERAL  AGRICULTURE. 


buds.  Cut  the  lower  end,  which  is  to  be  inserted  into  the 
cleft,  into  the  shape  of  a  wedge,  having  the  outer  edge 
thicker  than  the  inner 
(fig.  7.)  Cut  a  scion  so 
that  the  lowest  bud  will 
come  just  at  the  top  of 
this  wedge,  so  that  it 
will  be  near  the  top  of 
the  stock.  The  advan- 
tage of  cutting  the 
wedge  thicker  on  one 
side  is  illustrated  in 
figure  7,  which  shows 
how  the  pressure  of  the 
stock  is  brought  upon 
the  outer  growing  parts 
of  both  the^scjpn  and 
the  stock,  whereas  were 
the  scion  thicker  on  the 
inner  side  the  condi- 
tions would  be  reversed, 
and  the  death  of  the 

scion  would  follow.     To      Fl°'  6--^'  Orafting ;  a    the  scion; 

,        ,  '        •  b,  scions  inserted  in  cleft. 

make  the  contact  of  the 

growing  portion  doubly  certain,  set  the  scion  at  a  slight 
angle  with  the  stock  into  which  it  is  inserted  in  order  to 
cause  the  growing  portions  of  the  two  to  cross.  After  the 
scions  have  been  set,  complete  the  op- 
eration of  cleft  grafting  by  covering  all 
cut  surfaces  with  a  layer  of  grafting 
wax.  In  case  both  scions  "take,"  after 
a  good  growth  of  leaves  has  appeared, 
cut  off  evenly  at  the  stock  the  scion 
which  appears  the  weaker.  Wax  the 
cut  place.  Only  one  should  be  allowed 
to  continue  growing. 


FIG.  7. — Cross  sec- 
tion of  stock  and 
scion. 


MANUAL  OF  GENEEAL  AGRICULTURE. 


69 


59.     BUDDING. 

Material:     Budding  knife,  but  a  medium  or  a  large 
sized  pocket  knife  will  do  if  sharp,  and  raffia. 

There  are  numerous  styles  of  budding,  but 
only  the  one  in  most  common  use  will  be  de- 
scribed. Budding  is  one  of  the  most  econom- 
ical forms  of  artificial  reproduction  and 
each  year  witnesses  its  more  general  use.  It 
is  economical  in  the  amount  of  wood  used 
from  which  to  take  buds.  In  this  method  a 
single  bud  does  the  work  of  three  or  more 
upon  the  scion  used  in  grafting.  The  opera- 
tion of  budding  is  simple  and  can  be  done 
with  great  speed  by  expert  budders.  Bud- 
ding may  be  done  from  May  to  September. 
The  usual  plan  is  for  a  man  to  set  the  bud 
and  a  boy  follow  closely  and  do  the  tying. 

(a)  The  Bud. — Obtain  buds  from  wood 
of  the  present  season's  growth.     The  work 
of  budding  is  done  during  the  season  of  ac- 
tive growth.    Prepare  the  bud  stick  so  that 
the  petiole  or  stem  of   each   leaf  is  left  at- 
tached to  serve  as  a  handle  to  aid  in  pushing 
the  bud  home  when  inserting  it  beneath  the 
bark  of  the  stock.     This  is  what  is  usually 
called  a  shield  bud  and  should  be  cut  so  that 
a  small  portion  of  the  woody  tissue  of  the 
branch  is  removed  with  the  bud.  A  bud  stick 
is  shown  in  figure  8.     The  operation  of  cut- 
ting the  bud  is  illustrated  in  figure  9.     The 
stock  for  budding  should  be  at  least  as  thick 
as  an  ordinary  lead  pencil. 

(b)  The  Operation.— The  height  at  which 
buds  are  inserted  varies  with  the  operator. 
In  general  the  nearer  the  ground  the  better. 
Make  the  cut  for  the  insertion  of  the  bud  in 
the  shape  of  the  letter  T  (fig.  10,  a).  Usually 
the  cross  cut   is    made    not    quite    at    right 
angles  with  the  body   of   the   tree,  and  the 


70 


MANUAL  OF  GENEEAL  AGKICULTUKE. 


FIG.  9. — Cutting  the  bud. 


FIG.  10. — Budding — preparing  the 
stock. 

stem  to  the  T  starts  at  the  crosscut  and  extends  towards 
the  root  for  an  inch  or  more.  The  flaps  of  bark  caused  by 
the  insertion  of  the  two  cuts  (fig.  10,  b)  should  be  slightly 


MANUAL  OF  GENEKAL  AGEICULTUEE. 


71 


loosened  with  the  ivory  heel  of  the  budding  knife,  and  the 
bud,  grasped  by  the  leaf  stem  as  a  handle,  placed  under 
the  flap  and  firmly  pushed  into  place  until  its  cut  surface  is 
entirely  in  contact  with  the  peeled  body  of  the  stock  (fig. 
11,  a).  Eaffia  is  then  tightly  drawn  about,  above  and  be- 
low the  bud  to  hold  it  in  place  until  the  union  shall  be 
formed  (fig.  11,  b).  Bands  of  raffia  about  16  or  18  inches 
long  make  a  most  convenient  tying  material.  As  soon  as 
the  buds  have  united  with  the  stock,  the  raffia  should  be 
cut  in  order  to  prevent  girdling  the  stock.  This  done,  the 
operation  is  complete  until  the  following  spring,  when  all 
the  trees  in  which  the  buds  have  "taken"  should  have 
the  tops  cut  off  just  above  the  bud  (fig.  11,  c).  The  re- 
moval of  the  top  forces  the  entire  strength  of  the  root 
into  the  bud,  and  since  the  root  itself  has  not  been  dis- 
turbed by  transplanting,  a  more  vigorous  growth  usually 
results  from  the  bud  than  from  scions  in  whip  grafting 
when  the  roots  are  disturbed. 


FIG.  11. — Budding;  a,  inserting  the  ~bud;  b,  tying ;  c,  cutting  off 
the  top. 


72  MANUAL  OF  GENERAL  AGRICULTURE. 

60.     LAYING  OUT  AN  ORCHARD. 

In  laying  out  an  orchard  it  is  necessary  to  have  one 
side  and  one  end  of  the  field  at  right  angles.  Often  there 
are  regular  subdivisions  to  work  from ;  but,  if  there  are 
none,  these  two  lines,  called  base-lines,  may  be  estab- 
lished with  a  transit.  If  the  base-lines  cannot  be  estab- 
lished in  any  other  way,  proceed  as  follows  to  find  a 
square  corner.  Begin  at  the  corner  stake  and  measure 
off  60  feet  along  one  line  with  a  steel  tape,  and  put  in  a 
stake.  Then  from  the  starting  point  measure  off  80  feet 
as  nearly  at  right  angles  with  the  first  line  as  can  be 
judged  with  the  eye,  and  describe  an  arc  of  several  feet, 
holding  one  end  on  the  corner  stake.  Then  from  the  60 
foot  mark  measure  diagonally  across  to  a  point  on  the  arc 
that  is  100  feet  from  the  60  foot  mark  and  set  a  stake 
there.  The  three  stakes  will  then  form  a  square  corner. 
The  distances  30,  40  and  50  feet  would  do  as  well,  if  your 
tape  is  only  50  feet  long. 

There  are  two  methods  of  planting,  the  square  and 
the  equilateral  triangle,  but  as  the  square  method  is  the 
one  in  general  use,  this  method  alone  will  be  described. 

Make  at  least  thirty  stakes  about  half  an  inch  square 
and  one  foot  long.  These  may  be  split  out  of  redwood  or 
pine.  (If  six  inches  of  the  end  of  each  is  dipped  in  white- 
wash they  can  be  readily  seen,  and  should  any  of  the 
stakes  be  out  of  line  it  will  be  noticed  at  once.) 

Obtain  a  piece  of  No.  10  gauge  galvanized  wire ;  and, 
if  the  trees  are  to  be  20  feet  apart,  the  wire  should  be  202 
feet  long;  if  24  feet  apart  242  feet  long,  etc.  Attach  to 
each  end  of  the  wire  a  three-inch  iron  ring  by  bending  the 
wire.  Not  over  a  foot  from  the  original  end  of  either  end 
of  the  wire,  wrap  a  piece  of  small  wire,  making  three  laps 
and  solder  into  place. 

In  the  same  way  solder  into  place  a  small  piece  of 
wire  every  20  feet  along  the  wire  if  the  trees  are  to  be 
20  feet  apart.  In  handling  the  large  wire  be  careful  not 
to  get  a  kink  in  it  as  it  can  be  easily  broken  in  this  way. 

Having  established  base-lines,  place  a  stake  in  each 
corner  of  the  field,  set  stakes  for  ten  trees  for  each  stretch 


MANUAL  OF  GENERAL  AGRICULTURE.        73 

of  the  wire  by  stretching  the  wire  along  one  of  the  base- 
lines. Having  set  the  stakes  along  the  outside  line,  start 
at  the  same  end  of  the  field  again,  and  set  another  line  of 
stakes,  parallel  with  the  first  and  the  length  of  the  wire 
(chain)  from  it.  Follow  out  this  method  until  the  entire 
field  is  laid  out  in  checks.  With  the  check  lines  estab- 
lished it  is  only  necessary  now  to  set  stakes  at  the  20  foot 
marks  on  the  wire  where  the  trees  are  to  be  planted. 

61.     HOW  TO  PLANT  A  TREE. 

Materials  as  described  in  experiment.  Make  a  tree- 
setting  board  out  of  a  piece  of  pine  one  inch  by  4  inches 
by  four  feet  long.  About  an  inch  from  each  end  of  the 
board,  bore  a  hole  an  inch  or  so  in  diameter.  Then  saw 
a  triangular  notch  in  the  middle  of  one  side  of  the  board, 
making  the  notch  about  one  inch  across  and  one  and 
one-half  inch  deep. 

Make  two  stakes  small  enough  to  be  driven  through 
the  holes,  and  a  foot  in  length.  Place  the  notch  against 
the  stake  where  the  tree  is  to  be  planted  and  push  the 
stakes  through  the  holes  into  the  ground  then  remove 
the  center  stake  and  board.  Dig  a  hole  not  less  than 
eighteen  inches  in  diameter  and  eighteen  inches  deep. 
After  the  hole  is  dug,  replace  the  board  over  the  end  of 
the  stakes  and  plant  the  tree  with  the  trunk  resting 
against  the  center  notch.  In  setting  out  the  tree,  one 
person  should  hold  the  tree  in  an  upright  position  against 
the  notch  while  another  shovels  or  fills  in  loose  soil  around 
it,  first  spreading  out  the  roots  and  rootlets  in  as  natural 
position  as  possible.  The  surface  soil  should  be  put  in 
first  among  the  roots  taking  care  to  fill  every  interstice, 
thus  bringing  all  the  roots  in  direct  contact  with  the  soil. 
When  the  hole  is  two-thirds  full,  firm  the  earth  thoroughly 
about  the  roots,  but  before  doing  this  draw  the  tree  up 
to  its  permanent  position.  The  top  three  or  four  inches 
should  not  be  tramped  unless  the  ground  is  wet  from 
recent  rains.  Scoop  a  basin  out  around  the  tree  which 
will  hold  at  least  ten  gallons  of  water  and  apply  water 
either  by  bucket  or  irrigation.  The  following  day  draw 


74  MANUAL  OF  GENERAL  AGRICULTURE. 

in  loose  soil  and  fill  up  the  basin.  From  a  soil  mulch 
by  reducing  this  top  soil  to  as  fine  a  condition  of  tilth  as 
possible.  Guard  against  setting  too  deeply,  but  allow  for 
the  settling  of  soil  so  that  when  once  established  the  tree 
will  stand  about  as  it  did  at  the  time  of  removal  from 
the  nursery. 

62.     PROPAGATION  OF  THE  GRAPE. 

The  prevailing  method  of  propagating  the  grape  is 
by  growing  from  cuttings. 

There  are  two  distinct  types  of  vineyards.  We  may 
establish  a  vineyard  on  its  own  roots;  or  establish  a 
vineyard  on  resistant  roots. 

(a)     VINEYARD  ON  ITS  OWN  ROOTS. 

1.  Securing  the  Cuttings.     A  good  cutting  consists 
exclusively  of  one-year  old  wood;  that  is,  wood  which 
has  grown  the  previous  season.     The  cuttings  can  be  se- 
cured during  the  winter  pruning   (January),  when  the 
vines  are  dormant.    In  a  moist  soil  in  a  cool  region  they 
should  be  about  sixteen  inches  long  but  in  drier  regions 
about  twenty  inches  long.    It  is  not  possible  to  make  all 
cuttings   exactly  the   same   length   because   they   should 
terminate  at  each  end  at  a  node.     Cuttings  should  be 
from  three-eighths  to  five-eighths  of  an  inch  in  diameter. 
Take  great  care  not  to  injure  the  bud  at  either  terminal. 
Cut  off  all  intermediate  buds.     Cuttings  from  the  outer 
ends  of  long  canes  are  not  so  likely  to  root. 

2.  Care  of  Cuttings.     Cuttings  should  be  kept  dor- 
mant until  the  time  comes  for  setting  them  out.     This 
may  be   done   by  tying  them  in  bundles   of   convenient 
size,  in  this  case  put  fifty  in  a  bundle.     After  labeling 
by  means  of  a  stick  of  wood  tied  to  the  bundle,  dig  a 
trench  as  deep  as  the  length  of  the  bundles  on  the  north 
side  of  a  tight  board  fence  or  shed,  making  the  trench 
wide   enough  to  receive   them.     Place   them  in  it  in  a 
nearly  upright  position  and  cover  with  loose  earth  and 
on  top  put  some  straw.     They  should  be  in  moist  but  not 
wet  ground  as  too  much  moisture  rots  them. 


MANUAL  OF  GENEEAL  AGRICULTURE.  75 

3.  Planting  the  Cuttings.    The  cuttings  can  either  be 
planted  in  the  field  or  in  the  nursery.     If  they  are  to  be 
planted  directly  in  the  field,  planting  may  be  done  the  fol- 
lowing March  as  described  below.    Owing  to  the  fact  that 
only  from  50  to  80  per  cent  of  the  cuttings  will  take  root, 
or  form  vigorous  roots,  it  is  usual  and  far  more  desirable 
to  transfer  the  cuttings  to  the  nursery  in  March,  allowing 
them  to  take  root  and  remain  there  one  year.     (This  is 
the  method  we  shall  pursue.)     At  the  end  of  that  time 
only  vigorous  rooted   cuttings  need   be   used  and  thus  a 
much  more  perfect  stand  in  the  vineyard  can  be  obtained. 
In  planting  in  the  nursery  rows,  make  the  rows  four  feet 
apart  for  horse  cultivation  and  two  feet  apart  for  hand 
cultivation,  in   either   case    planting   them    three  to  four 
inches  apart  in  the  rows.    The  nursery  should  be  in  loose, 
moist  soil  so  that  a  good  root  system  will  develope.    Leave 
the  upper  bud  just  above  the  surface  of  the  ground. 

4.  Transferring  to  Vineyard.     A  year  later  when 
planting  in  the  vineyard  it  is  customary  in  heavy  soils  to 
plant  8  by  8  feet  apart,  but  in  light  soils  12  by  12  feet 
apart,  laying  out  the  vineyard  the  same  as  an  orchard. 
Dig  the  holes  the  width  of  a  spade  and  the  length  of  the 
cutting  in  depth.    Leave  the  top  soil  to  one  side  so  that  it 
can  be  put  into  the  hole  first  when  filling. 

When  all  or  a  part  of  the  holes  are  dug,  dig  up  tho 
cuttings  and  if  not  very  moist  place  them  in  water  for  at 
least  24  hours ;  otherwise  transfer  directly  to  the  vineyard 
after  digging  and  plant  as  soon  as  possible — in  any  case 
the  same  day,  but  before  planting  trim  the  roots  back  to 
from  2  to  3  inches.  In  planting  place  a  cutting  in  a  hole 
and  shovel  in  the  top  soil  first  so  that  when  the  cutting  is 
leaning  against  the  side  of  the  hole  there  will  be  one  bud 
just  above  the  surface  of  the  ground  when  the  filling  is 
complete.  Continue  filling  the  hole  until  it  is  about  half 
full,  then  tramp  down  with  the  foot.  Continue  filling  the 
hole  so  that  when  the  hole  is  completely  filled  the  bottom 
soil  is  on  top.  Again  tramp  down  the  soil  about  the  cut- 
ting and  finally  leave  a  soil  mulch  over  the  entire  area 
covered. 


76  MANUAL  OF  GENERAL  AGRICULTURE. 

b.    VINEYARD  ON  RESISTANT  ROOTS. 

American  wild  vines  are  characterized  by  marked 
differences  in  degree  of  resistance  to  Phylloxera,  a  very 
destructive  insect.  By  selection  a  few  wild  types  have 
been  secured  that  are  almost  immune  to  the  attacks  of  this 
insect.  For  a  deep  soil  Rupestris  St.  George  is  used  as  the 
stock;  for  dry  soils  or  on  hill  sides  Reparia  x  Rupestris 
3309.  The  disease  does  not  spread  much  in  sandy  soil  so 
that  it  is  advisable  to  establish  the  vineyard  on  its  own 
roots  in  this  case. 

A  resistant  vineyard  may  be  established  in  either  of 
two  ways:  1.  By  Field  grafting ;  or  2.  By  Bench  graft- 
ing. 

1.  Field  Grafting.     This   may   be   accomplished   by 
planting  resistant  cuttings  directly  in  the  vineyard  and 
field  grafting,  or  grafting  in  the  field  the  following  win- 
ter.   Only  a  50  to  80  per  cent  stand  can  be  obtained  by  this 
method,  hence  it  is  not  in  favor. 

2.  Bench  Grafting.     Secure  cuttings  from  resistant 
vines  such  as  Rupestris  St.  George  or  Reparia  x  Rupestris 
3309  during  the  dormant  period,  or  at  the  time  of  prun- 
ing (January.)     If  necessary  secure  these  cuttings  from  a 
nurseryman.     Likewise  secure    scions    from    the    desired 
varieties  to  be  propagated.     The  scions  may  be  any  con- 
venient length — two  or  three  feet.     Select  both  cuttings 
for  stock  and  cuttings  for  scions  from  strong  growing 
healthy  vines.    They  should  be  of  the  same  size  to  be  ac- 
curately matched  in  grafting.     Heel  them  in  until  some 
convenient  time  in  late  winter  or  early  spring  (March), 
then  dig  them  up  and  graft.     (The  work  is  usually  done 
on  a    bench,  hence    the    name  "bench    grafting.")     The 
scions  should  have  one  bud  and  should  be  long  enough  to 
handle  while  grafting — two  or  three  inches.     Do  not  tie 
with  raffia  or  use  grafting  wax.    Keep  the  grafted  stock  in 
bundles  of  convenient  size  in  moist  sand  in  a  warm  place, 
or  preferably  in  a  warm  room  when  a  callus  will  form  at 
each  joint.    A  month  later   they   may  be   planted  in  the 
nursery.     The  following  spring  transfer  to  the  vineyard. 
In  planting  any  kind  of  rooted  vines  prune  the  roots  to 


MANUAL  OF  GENERAL  AGRICULTURE.  77 

two  or  three  inches  in  length  at  the  time  of  planting.  This 
method  of  establishing  a  vineyard  is  the  accepted  French 
one  and  has  proved  successful  in  California. 

63.     PROPAGATION  OF  THE  ORANGE. 

(The  following  applies  to  the  lemon  and  pomelo  as 
well  as  to  the  orange.) 

The  propagation  of  the  orange  differs  considerably 
from  the  propagation  of  deciduous  trees. 

1.  Selecting  and   Planting  the   Seed.     Select  seeds 
from  the  sweet  orange,  Florida    sour    orange  or    pomelo 
with  which  to  grow  the  stock.    Plant  the  seeds  in  a  seed 
bed  sheltered  by  a  lath  house  or  in  the  open,  but  in  either 
case  the  seed  bed  should  be  well  drained,  mixed  with  a 
light  soil  and  mulch  and  finally  covered  with  a  layer  of 
light  sand.    In  preparing  in  spring  plant  the  seeds  an  inch 
deep  and  1%  inches  apart. 

2.  Digging  the  Seedlings.    One  year  later  remove  the 
seedlings  to  the  nursery,  planting  them  in  rows.    The  rows 
should  be  about  39  inches  apart  for  horse  cultivation,  but 
for  hand  cultivation  16  inches  is  sufficient.    In  either  case 
plant  the  trees  about  one  foot  apart  in  the  rows. 

3.  Budding  the  Seedlings.    The  seedlings  should  be 
budded  after  being  in  the  nursery  either  one  or  two  years. 
A  week  or  two  before  the  operation,  strip  the  seedlings  by 
removing  all  leaves  and  thorns  from  the  lower  six  inches 
of  the  trunk  to  make  room  for  the  bud.     Insert  the  bud 
two  or  three  inches  above  the  ground.     The  best  time  to 
bud  is  in  the  spring.    Budding  may  also  be  done  in  mid- 
summer or  in  the  fall.    The  growth  from  the  summer  buds 
is  likely  to  be  killed  by  frost  during  the  first  winter.    Fall 
buds  lie  dormant  during  winter  and  start  the  following 
spring.     When  the  bud  attains  6  to  8  inches  growth,  re- 
move the  top  of  the  tree  as  shown  in  figure  11,  c. 

4.  Transferring  to  Orchard.    After  one  or  two  years 
the  trees  should  be  transferred  to  the  orchard.    The  most 
common  method  is  to  "ball  them,"  that  is,  to  remove  a 
ball  of  earth  with  the  roots,  tying  a  sack  around  them  to 
keep  the  soil  from  falling  away. 


78  MANUAL  OF  GENEKAL  AGRICULTURE. 

The  usual  method  of  planting  is  in  squares.  The  trees 
should  not  be  less  than  20  feet  by  20  feet  apart. 

64.     PRUNING  FRUIT  TREES,  VINES  AND  BUSHES. 

To  know  how  to  prune  the  various  fruits,  we  must 
know  upon  what  kind  of  branches  each  bears  its  fruit  and 
thj/age  of  the  branches. 

The  Age  of  Branches.  Take  a  pear  branch  and,  be- 
ginning at  the  tip,  follow  it  back  until  you  find  a  point 
where  there  is  a  slight  bulge  and  many  tiny  scars.  This 
marks  the  end  of  one  year's  growth  and  the  beginning  of 
another.  Follow  on  down  the  branch  and  determine  its 
age.  In  most  cases'  the  age  of  a  branch  of  a  fruit  tree  can 
be  determined  in  this  way.  With  many  of  the  vines  and 
bushes  these  rings  are  lacking,  or  are  not  so  noticeable, 
and  the  color  and  condition  of  the  bark  is  a  better  guide. 

The  Pear — fruit  bearing  habit.  The  short  branches 
bearing  the  fruit  are  called  fruit  spurs.  What  are  the 
ages  of  the  various  parts  of  the  main  branch  which  bear 
the  spurs?  The  spurs  are  each  one  year  younger  than  the 
branch  upon  which  they  are  borne.  Why?  If  an  un- 
branched  spur  produces  a  fruit  this  year,  it  also  produces 
a  vegetative  bud  at  the  base  of  the  fruit,  which  next  year 
continues  the  growth  of  the  spur  and  produces  a  fruit  bud 
in  the  fall.  This  causes  the  zigzag  growth  characteristic 
of  pear  and  apple  spurs. 

Draw  a  pear  spur  and  a  portion  of  the  main  branch, 
showing : 

1.  Annual  ring  of  growth. 

2.  Fruit  scars. 

3.  Fruit. 

4.  Vegetative  bud. 

How  old  is  this  spur?  What  is  the  oldest  wood  on  the 
branch  having  fruit  bearing  spurs  ?  The  youngest  ? 

Pruning.  It  usually  requires  two  or  more  years  for 
a  young  branch  to  produce  fruit ;  such  a  branch  may  bear 
fruit  for  many  years.  As  a  branch  grows  out  year  after 
year,  the  fruit  bearing  area  moves  out  also,  the  older  parts 


MANUAL  OF  GENERAL  AGEICULTUEE.  79 

ceasing  to  produce.  If  we  head  back  a  branch,  the  fruit- 
ing area  cannot  be  renewed  until  new  branches  are  formed. 

A  fruit  spur  irxay  change  its  function  and  become  a 
branch,  which  in  time  may  produce  new  fruit  spurs.  Ef 
we  prune  away  too  much  foliage  bearing  wood,  the  tree 
restores  the  balance  by  changing  spurs  to  branches.  Ex- 
amine branches  and  find  examples  of  this. 

If  we  cannot  head  in  and  must  avoid  excessive  prun- 
ing, how,  then,  should  we  prune  the  pear? 

The  Apple.  The  fruit  bearing  habit  of  the  pear  and 
apple  is  practically  the  same.  Examine  an  apple  branch 
and  prove  this. 

The  Peach — fruit  bearing  habit.  In  this  case  the  fruit 
is  not  borne  on  spurs,  but  directly  on  one-year-old 
branches.  Occasionally  these  branches  are  so  short  as  to 
look  like  spurs.  On  a  branch  which  has  grown  this  sea- 
son, find  a  single  node  which  has  produced  three  leaves; 
carefully  remove  the  leaves  and  study  the  buds  in  their 
axes.  Next  spring  the  two  outer  ones  will  try  to  produce 
flowers  and  the  middle  one  leaves. 

Notice  the  following :  (1)  Wood  older  than  one  year 
bears  no  fruit.  (2)  The  fruit  is  borne  on  the  middle  and 
lower  portions  of  one-year  wood.  (3)  Only  vigorous  one- 
year  wood  produces  fruit  in  quantities.  (4)  The  upper 
buds  tend  to  produce  branches.  (5)  Compare  the  buds 
on  this  season's  wood  with  what  came  from  the  buds  on 
last  season's  wood.  Draw  a  branch  which  has  grown  this 
season  (first  removing  the  leaves)  and  indicate  the  nodes 
at  which  fruit  buds  are  being  formed. 

Pruning.  To  produce  fruit,  we  must  have  a  vigorous 
growth  of  new  branches  each  year.  How  may  we  prune 
the  peach  to  secure  this? 

The  Cherry — fruit  bearing  habit.  In  the  cherry  we 
have  fruit  borne  similar  to  the  pear,  and  also  similar  to 
the  peach,  that  is,  we  find  some  fruit  on  one-year  wood 
and  some  on  fruit  spurs.  Near  the  base  of  this  season's 
wood  you  will  find  single  buds  that  are  more  plump  than 
those  further  up  the  branch;  these  will  bear  fruit  next 
year.  There  is  no  foliage  or  vegetative  bud  at  this  point, 


80  MANUAL  OF  tTENERAL  AGRICULTURE. 

so  that  the  lower  portion  of  the  branch  remains  bare  after 
the  fruit  is  picked.  The  side  branches  are  all  grouped  on 
the  upper  part  of  the  year's  growth.  The  age  of  a  cherry 
tree  can  frequently  be  told  by  counting  these  groups  of 
side  branches. 

Pick  off  a  spur  and  notice  that  its  growth  has  been 
straight,  and  not  zigzag,  as  in  the  pear.  The  central  bud 
of  the  cluster  is  a  foliage  bud  and  continues  growth  year 
after  year.  It  is  more  pointed  than  the  surrounding  fruit 
buds.  "What  is  the  age  of  the  oldest  branch  that  you  can 
find  bearing  fruit  spurs? 

Pruning.  Only  a  very  small  amount  of  the  fruit  is 
borne  on  one-year  wood.  It  is  the  fruit  spurs  which  are 
important.  With  this  point  in  mind,  how  would  you 
prune  the  cherry? 

Picking  Fruits  which  Possess  Fruit  Spurs.  If  a  spur 
is  broken  off,  there  are  no  buds  left  to  renew  it.  In  pick- 
ing, the  fruit  should  be  separated  from  the  spur.  Many 
cherry  trees  become  unproductive  because  the  pickers 
have  broken  off  the  clusters  of  cherries  and  thus  removed 
the  spurs. 

The  Grape — fruit  bearing  habit.  The  grape  is  differ- 
ent from  both  the  pear  and  the  peach.  In  the  winter  you 
can  find  no  fruit  buds;  all  buds  then  are  vegetative.  In 
the  spring  from  each  bud  comes  a  cane  which  produces 
flowers  and  fruit  that  same  season.  Examine  a  grape  cane 
and  verify  this.  Notice  that  the  fruit  is  produced  usually 
at  the  second,  third  and  fourth  nodes  only,  that  is,  eacli 
bud  found  on  the  vine  in  winter  tries  to  produce  a  cane 
which  will  bear  from  two  to  three  fruit  clusters ;  therefore 
by  limiting  the  number  of  buds  which  we  leave  on  the 
vines,  we  limit  the  number  of  fruit  clusters  which  the  vine 
will  produce.  The  maximum  number  of  good  clusters  that 
a  vine  will  produce  ranges  from  twenty-five  to  fifty. 

Pruning.  The  grape  must  be  cut  back  every  year  so 
as  to  have  from  fifteen  to  twenty  buds  only. 

Blackberries  and  Raspberries — fruit  bearing  habit. 
These  produce  fruit  on  the  branches  grown  this  season  in 
the  same  way  as  the  grape.  The  first  year  a  straight  cane 


MANUAL  OF  GENERAL  AGRICULTURE.  81 

is  sent  up,  the  second  year  this  forms  side  branches,  which 
terminate  in  fruit  clusters.  After  the  fruit  matures  the 
cane  dies. 

Pruning.    How  would  you  prune  the  raspberry? 

(Let  the  teacher  arrange  field  exercises  in  winter  and 
prune  as  many  different  kinds  of  fruits  as  are  available.) 

65.  STRUCTURE  AND  NATURE  OF  FUNGI. 

Materials:  Mouldy  bread,  (see  exercise)  dish,  lens 
and  compound  miscroscope. 

The  piece  of  bread  furnished  has  been  moistened,  a 
bit  of  mouldy  stable  manure  placed  upon  it,  then  placed 
in  the  dish  and  kept  covered  for  a  week. 

1.  Mycelium  of  the  Fungus   (pi.  fungi.)     Examine 
with  a  lens,  notice  the  white,  mouldy  growth — the  myce- 
lium of  the  fungus.    It  corresponds  to  the  roots,  stems  and 
leaves  of  other  plants.    It  takes  its  food  from  the  bread. 

2.  Sporangium.     Notice  that  the  dark  color  is  due 
to  black  specks  attached    to    the    mycelium    threads    by 
means  of  a  stalk.     These    are    spore    cases.     Each  one  is 
called   a    sporangium.     Some    are    white.     They    are  the 
young  unripe  ones.     The  spores  correspond  to  seed  and 
the  sporangium  corresponds  to  a  pod.    Mount  some  of  the 
fungus  in  a  drop  of   water    and   examine    with    the  low 
power  of  a  compound  microscope.    Make  drawings  of  the 
mycelium,  sporangium  and  spores. 

66.  STRUCTURE  AND  NATURE  OF  BACTERIA. 

Materials:  Potato,  needle,  compound  miscroscope. 
(Let  the  teacher  send  to  the  State  Hygenic  Laboratory, 
Berkeley,  Cal.,  and  ask  for  the  loan  of  a  box  of  bacterio- 
logical specimens  prepared  especially  for  schools.  There 
will  be  no  expense  except  for  express  both  ways.) 

Bacteria  are  the  smallest  of  all  known  plants.  They 
are  to  be  found  almost  everywhere,  on  the  earth,  inside 
and  outside  the  bodies  of  living  animals  and  plants,  in 
water,  in  milk,  and  on  the  dust  particles  of  the  air.  Wher- 
ever moisture  and  food  are  present,  some  species  will  grow 
and  multiply  hindered  only  by  extremes  of  temperature, 


82  MANUAL  OF  GENEEAL  AGEICULTURE. 

light,  oxygen,  or  toxic  substances.  A  few  are  known  to 
cause  diseases  of  man  and  animals,  a  rather  large  number 
(about  125)  are  now  known  to  cause  diseases  in  plants. 

Some  Common  Bacteria.  Their  Structure  and  Nature. 
In  the  material  provided,  the  bacteria  are  growing  on 
slices  of  cooked  potato  exposed  to  the  air  of  laboratory  for 
three  minutes,  covered,  and  then  set  in  a  warm  place  for 
several  days.  What  conditions  favorable  to  plant  growth 
were  provided?  Observe: 

1.  The  more  or  less  circular  patches  of  various  sizes 
and  colors  on  the  surface  of  potato — the  colonies  of  bac- 
teria.   How  can  you  tell  them  from  molds?    Note  the  dif- 
ference in  form  and  character  of  margins  of  different  col- 
onies.    Each  colony  was  formed  by  the  multiplication  of 
a  single  bacterium. 

2.  Compare  different    colonies  as  to    nature  of    the 
surface,  moist,  dry,  shiny,  dull,  smooth,  wrinkled,  etc. 

3.  Note  that  some  colonies  are  covered  with  a  skin 
or  pellicle,  made  up  of  bacteria  stuck  together  by  their 
gelatinous  wall  and  dried  by  exposure  to  air.    With  needle, 
determine  toughness  of  pellicle. 

4.  Bacteria  feed  on  substances  dissolved  from  the 
potato.     Some  colonies  penetrate  the  potato,  others  sim- 
ply pile  up. 

5.  Bacteria,  in    their    growth,  produce    gases    with 
offensive  odors,  such  as  the  odor  from  the  potato.     The 
common  odors  of  decay  are  of  this  nature.    Map  the  sur- 
face of  the  potato. 

6.  With  the  point  of  the  needle  touch  the  different 
colonies,   drawing   the   needle   slowly   away.      Note   that 
some  are  viscid,  drawing  out  into  long  threads  as  the 
needle  is  removed.    Clean  your  needle. 

Selecting  a  colony  with  wrinkled  surface,  remove 
from  the  smooth,  glistening  margin  a  bit  on  the  point  of 
your  needle.  Stir  it  into  a  drop  of  water  on  a  clean  slide. 
How  does  it  affect  the  water?  Why? 

7.  Under  low  power,  note  the  finely  granular  appear- 


MANUAL  OF  GENEEAL  AGRICULTURE.  83 

ance  of  the  water.  Can  you  make  out  the  individual 
plants?  This  power  of  your  microscope  magnifies  50 
times.  Selecting  a  thin  place  in  the  mount  turn  on  the 
high  power  and  observe : 

8.  The  very  small,  short  rod-shaped  bacteria  (  magni- 
fied about  500  times.) 

9.  In  many  cases  longer  rods  made  up  of  2  or  more 
plants  fastened.    Each  plant  is  a  single  bacterium.    They 
multiply  by  the  simple  division  of  each  plant  into  two. 
They  may  reach  their  full  growth  in  less  than  half  an 
hour.    Draw. 

Make  mounts  on  clean  slides  from  differently  appear- 
ing colonies.  Compare  the  bacteria  from  these  different 
colonies  as  to  form,  size,  etc.  Do  they  seem  to  be  all  alike  ? 
Are  all  the  bacteria  in  any  given  colony  alike?  (Do  not 
use  the  same  slide  more  than  once  without  thorough  wash- 
ing and  clean  your  needle  each  time  before  making  a 
transfer).  Are  the  bacteria  from  different  appearing  colo- 
nies always  different  in  form,  size,  motility,  etc.  ? 

PART  V— ENEMIES  OF  CROPS. 
67.     APPLE  SCAB. 

Of  all  diseases  of  the  apple,  this  is  the  commonest  and 
best  known  to  the  growers.  It  is  the  one  fungus  disease 
for  which  they  spray.  It  is  world  wide,  occurring  prac- 
tically wherever  the  apple  is  grown.  While  there  is  a 
marked  difference  in  the  susceptibility  of  varieties,  all  will 
sufor  some  under  conditions  especially  favorable  to  the 
fungus  causing  the  disease.  The  scab  of  the  pear  is  very 
similar  in  its  symptoms  to  that  of  the  apple,  but  is 
caused  by  a  distinctly  different  species  of  fungus,  which, 
however,  is  closely  related  to  the  apple  scab  fungus.  In 
either  case  the  remedy  is  the  same. 

THE  DISEASE. 

SYMPTOMS.  The  disease  affects  the  leaves,  flowers, 
fruit  and  rarely  the  twigs.  It  lives  over  winter  on  fallen 
leaves. 


84  MANUAL  OF  GENEEAL  AGEICULTURE. 

On  the  Leaves.  The  first  evidence  of  the  disease  in 
the  spring  is  upon  the  unfolding  leaves.  The  scab  spots 
usually  appear  first  upon  the  under  surface.  Later  the 
upper  surface  Becomes  infected.  Examine  the  leaves  pro- 
vided and  observe : 

1.  The  size,  form  and  character  of   the    spot.     The 
radiating  character  of  the  markings  of  the  lesion.     To 
what  due  ? 

2.  The  character  of  the  injury  to  the  leaf.    Does  the 
injury  show  on  the  surface  opposite  the  spot  ? 

3.  Difference  in  the  character  of  the  upper  and  un- 
der surface  of  the  leaf  itself.     Of  the  scab  spots  on  the 
two  surfaces  of  the  leaf. 

4.  The  variation  in  the  character  of  the  scab  spots 
on  different  leaves.     Make  drawings  to  show  the  charac- 
ters of  the  scab  spots  on  the  upper  and  under  surface  of 
the  leaves. 

On  the  Fruit.  Where  the  infection  of  the  calyx  is  not 
severe  enough  to  prevent  the  fruit  from  setting,  the  apple 
as  it  enlarges  shows  the  enlarging  scab  spots  which  be- 
come very  evident  as  the  season  advances.  In  the  young 
apples  provided.  Observe : 

5.  The  black  scab  spots.    Their  form,  size  and  effect 
on  the  fruit.    To  what  region  on  the  apple  are  they  largely 
confined  ?    Why  ? 

6.  The  f elty  black  center  of  the  spot.    In  some  cases 
this  felt  is  gone  at  the  center  of  the  spot,  which  is  hard, 
of  a  reddish  brown  color  and  often  cracked. 

7.  The  papery  rim  of  border  of  the  spot.    Best  seen 
in  the  younger  spots.     This  consists  of  the  cuticle  of  the 
apple  that  had  pried  loose  by  the  fungus  as  it  spreads  out 
from  the  center  of  the  spot.    Make  drawings  to  show  the 
points  brought  out  in  5,  6  and  7. 

Sometimes  these  spots  cause  a  dwarfing  of  the  apple 
on  the  affected  side  so  that  they  become  one  sided. 

The  apple  scab  is  caused  by  the  fungus  known  as 
Venturia  inequalis.  It  lives  upon  the  surface  of  the  host 


MANUAL  OF  GENEEAL  AGEICULTUBE.  85 

or  nearly  so,  prying  off  the  cuticle  and  applying  its  my- 
celium closely  to  the  host  tissue. 

Control.  One  spraying  just  before  and  one  immedi- 
ately after  blossoming  are  most  important  for  its  control. 
If  the  scab  is  serious  it  may  be  necessary  to  spray  a  third 
time.  The  spray  used  is  known  as  Bordeaux  Mixture.  It 
is  made  of  copper  sulfate  and  lime.  Directions  for  its 
preparation  are  given  in  any  of  the  references  in  Part  V. 

68.     FIRE  BLIGHT. 

Materials :  Read  the  experiment.  Obtain  Cornell  Uni- 
versity College  of  Agriculture,  Bulletin  272.  In  sections  5 
and  6  obtain  specimens  at  blossoming  time  and  press  them. 
Later  in  7  obtain  fruit  and  preserve  in  a  five  per  cent  solu- 
tion of  formalin,  to  which  has  been  added  enough  copper 
sulfate  to  just  color  the  water.  The  latter  will  hold  the 
color  in  the  fruit.  Whenever  possible  fresh  material 
should  be  used. 

This  is  the  most  common  and  best  known  bac- 
terial disease  of  plants  occurring  in  this  country.  It 
affects  apples,  pears,  quinces  and  occasionally  plums,  apri- 
cots, and  a  few  ornamental  and  wild  plants  related  to  the 
apple  family.  The  affected  tissues  are  killed  outright. 

Symptoms.  The  symptoms  of  this  disease  will  be 
studied  in  the  order  in  which  they  manifest  themselves 
during  the  season  on  different  parts  of  the  tree,  beginning 
with  the  first  activity  of  the  disease  in  the  spring. 

The  hold-over  canker  is  the  source  for  the  first  infec- 
tion in  the  blossoms  in  the  spring.  Typical  cankers  on  the 
limbs  of  apple  and  pear  trees  have  been  provided.  Study 
the  specimens  before  you  carefully  and  observe : 

1.  The  smooth,  more  or  less  sunken  area  in  the  bark, 
its  margin  sharply  defined  by  a  definite  crack  in  the  epi- 
dermis— the  canker.  In  active  cankers  this  margin  is  not 
sharply  defined.  Note  the  diseased  spur  or  shoot  at  the 
center  of  each  canker. 


86  MANUAL  OF  GENERAL  AGKICULTURE. 

2.  The  margin.    Note  that  it  is  irregular,  the  crack 
being  formed  by  ^he  drying  away  of  the  diseased  tissue 
from  the  healthy  when  the  active  progress  of  the  disease 
was  suddenly  checked.     Dry  or    cold   weather   may  thus 
check  the  spread  of  the  canker.     These  specimens  were 
taken  in  the  autumn  or  winter. 

3.  The  surface  of  the  canker.    Note  that  it  is  smooth, 
seldom  roughened  or    wrinkled.     It  is    often   checked  in 
from  the  margin  by  drying.     Compare  with  the  healthy 
bark  in  this  respect.    Locate  the  lenticles. 

4.  Make  a  careful  drawing  of  the  canker  you  have 
studied.    Label  fully. 

These  cankers  are  formed  during  the  summer  and 
early  autumn,  and  in  many  of  them  the  bacteria  pass  the 
winter  dormant,  or  only  slightly  active  in  the  partially 
living  tissues  along  the  margin.  With  the  increased  tem- 
perature and  rise  of  sap  in  the  spring,  these  bacteria  be- 
come active,  spread  rapidly  into  the  adjoining  healthy 
tissue,  increasing  the  area  of  the  canker  and  oozing  out 
through  the  lenticles  to  the  surface  in  sticky,  milky  drops. 
If  active  cankers  are  available  make  a  careful  drawing, 
showing  large  viscid,  milky  drops  that  have  oozed  out. 
(See  Fig.  16  N.  Y.  Cornell  Bulletin  No.  272.) 

5.  Blossom  Blight.    Bees  and  flies  visit  these  active 
cankers  in  the  spring  to  feed  on  exuding  sap  and  then 
visit  the  opening  blossoms,  where  they  leave  behind  them 
some  of  the  blight  bacteria  with  which  they  are  smeared. 
Here  in  the  nectar  and  in  the  injuries  made  by  the  insects' 
claws  in  the  tender  tissue  of  the  fiower,  the  bacteria  mul- 
tiply rapidly,  killing  the  blossom.     Study    the    specimen 
provided  or  Fig.  6,  Cornell  Bui.  272.     Observe : 

6.  The  dead  and  blackened  flowers.     The  leaves  of 
the  spur  are  also  dead   and   brown.     The   bacteria    have 
spread  down  the    pedicles   in   the    spur.     The    dead  and 
blackened  blossom  spurs  are  usually  the  first  striking  evi- 
dence of  the  disease  in  the  spring.     The  oozing  cankers 


MANUAL  OF  GENERAL  AGRICULTURE.  87 

are  usually  overlooked.    Make  drawing  of  a  blighted  blos- 
som spur. 

7.  Fruit  Blight.    Frequently  only  one  blossom  on  a 
spur  is  infected  and  by  the  time  the  bacteria  have  killed 
it  and  worked  their  way   down   the   pedicle   to  the  spur 
itself,  the  uninfected  blossoms  have  developed  fruit  of  a 
considerable  size.     From  the  spur  the  bacteria  now  work 
into   the    base   of   these   fruit   pedicles    and   by   way   of 
them  to  the  growing  fruit.    Study  Fig.  6,  Cornell  Bui.  272. 
The  curculio  and  aphids  frequently  introduce  the  bacteria 
into  the  fruit  through  their  punctures.     The  disease  does 
not  always  enter  the  fruit  by  the  pedicle.     Note  that  the 
leaves  of  the  spur  are  also  dead  and  shriveling.    In  rainy, 
muggy  weather  the    bacteria    ooze    from    these    blighted 
fruits  and  blossoms  in  sticky  drops  as  they  do  from  the 
hold-over  cankers. 

8.  Twig  Blight.     The    bacteria    from    the    diseased 
blossoms  and  fruits  are  carried  by  sucking  insects  to  the 
tips  of  the  growing  shoots  and  waterspouts  and  are  there 
introduced  through  the  wounds  or  punctures  made  by  the 
insects  into  the  tender,  succulent  tissues.    Here  they  mul- 
tiply rapidly,  killing  the  shoot,  causing  the  form  of  the 
disease  commonly  known  as  "Twig  Blight."     Blighted 
twigs  have  been  taken    from    the    tree    in    summer    and 
pressed.    Examine  the  specimen  provided  and  observe : 

9.  The  contrast  between  the    diseased    and  healthy 
portions  of  the  twig  in  both  the  twig  and  leaves.   You  may 
be  able  to  find  the  dried  ooze.    Draw  the  blighted  twig. 

10.  In  some  of  the  specimens  note  that  the  dormant 
buds  in  the  axils  of  the  leaves  just  below  the  blighted  por- 
tion have  been  prematurely  forced.    Explain  this. 

The  organism  that  causes  this  disease  is  Bacillus  amy- 
lovorus.     See  Fig.  6,  Cornell  Bui.  272. 

11.  Control  of  the  Disease.    No  method  of  protecting 
the  trees  by  means  of  sprays  is  effective  because  it  is  im- 
possible to  reach  the  bacteria.    The  disease  can  be  effect- 


88  MANUAL  OF  GENEEAL  AGRICULTURE. 

ively  controlled  by  inspecting  the  orchard  at  least  once  a 
week  during  the  growing  season,  beginning  as  soon  as  the 
blossoms  begin  to  fall,  cutting  out  the  diseased  portions 
and  disinfecting  the/ cut  surfaces  with  corrosive  sublimate 
solution  made  by  dissolving  one  tablet  in  a  pint  of  water. 
(See  Cornell  Bui.  272.)  If  diseased  trees  are  available  see 
if  you  can  control  the  disease  in  this  way. 

Question :    Point  out  the  practical  importance  of  each 
of  the  following  facts  about  Fire  Blight : 

1.  It  is  a  bacterial  disease. 

2.  It  occurs  only  in  North  America. 

3.  The  bacteria  causing  the  disease  pass  the  winter 
in  hold-over  cankers  in  any  of  its  numerous  hosts. 

4.  The  bacteria    get    into    the    host    only    through 
wounds. 

5.  The  chief  agents  of  dissemination  are  certain  in- 
sects. 

6.  The    bacteria    are    usually    introduced    into    the 
young  and  growing  parts  of  the  host,  where  in  these  suc- 
culent tissues  they  multiply  and  develop  the  disease  very 
rapidly. 

69.     THE  MOUTH-PARTS  OF  INSECTS.* 
Materials:    Lens,  needle,  forceps,  grasshopper,  honey 
bee,  squash  bug,  moth. 

Insects  that  injure  plants  are  of  two  classes.  The 
distinction  between  these  two  classes  is  in  the  form  of 
their  mouth-parts.  One  class  has  its  mouth-parts  fitted 
for  biting  or  chewing,  while  the  other 
class  has  them  fitted  for  sucking.  Meth- 
ods of  destroying  insects  are  based  on  this 
difference  in  the  structure  of  the  mouth. 
Insecticides  of  one  kind  are  used  for  kill- 
ing insects  with  a  mouth  fitted  for  biting. 
Such  insects  usually  feed  upon  the  leaves 
of  plants.  Poisons  of  different  kinds  are 
therefore  sprayed  or  dusted  upon  the 

leaves.     The  poison  is  taken  up  by  the  in-pIG    12. The  head 

sect  with    its  food,  producing    in  its  ali-    of  a  locust. 
*From  Cornell  Rural  School  Leaflet. 


MANUAL  OF  GENERAL  AGRICULTURE.  89 

mentary  canal  changes  that  eventually  cause  its  death. 
Insecticides  of  an  entirely  different  kind  are  used  for  suck- 
ing insects.  These  insecticides  usually  contain  a  resin, 
alkali,  oil,  or  a  strong  caustic,  which  corrodes  or  contracts 
and  shrivels  the  body  of  the  insect,  covers  the  breathing 
pores  located  along  each  side  of  the  insect's  abdomen,  and 
in  this  way  causes  its  death. 

To  determine  what  kind  of  insecticide  shall  be  used 
to  destroy  any  particular  kind  of  insect,  it  is  necessary  to 
determine  first  what  kind  of  mouth-parts  it  has.  To  be 
able  to  decide  this  question  accurately,  something  must  be 
known  of  the  more  essential  structures  of  an  insect's 
mouth. 

Mouth-parts  Fitted  for  Biting.  Observe  that  the  head 
of  an  insect  may  be  held  either  horizontally  or  vertically ; 
if  horizontally,  the  mouth  opening  is  at  the  extreme  front 
end  of  the  head ;  if  vertically,  the  mouth  opening  is  at  its 
lower  end  on  a  plane  with  the  under  side  of  the  body.  The 
locust  or  ordinary  grasshopper,  which  has  been  selected 
as  typical  for  those  insects  with  biting  mouth-parts,  holds 
its  head  vertically  with  the  moutli  opening  below.  I"  ig.  12. 
The  locust  is  especially  suitable  for  study,  not  omy  be- 
cause specimens  can  be  obtained  easily,  but  also  because 
it  is  truly  representative  of  the  biting  type  of  insect. 

The  locust  (grasshopper)  mouth-parts  consist  of 
seven  distinct  portions:  an  upper  lip  (labrum),  two  biting 
jaws  (mandibles),  two  holding  jaws  (maxillae — singular 
maxilla),  the  tongue  (hypopharynx),  and  a  lower  lip  (la- 
bium.)  The  labrum  is  a  movable  nap  closing  the  mouth 
opening  in  front.  I1  ig.  13.  The  mandibles,  ^  ig.  13  md,  are 
strong,  toothed  jaws  with  sharp  edges  which  move  side- 
wise  just  behind  the  labrum  and  are  used  for  cutting  and 
grinding  the  food.  The  maxillae,  Fig.  13  mx,  are  situated 
just  behind  the  mandibles  and  like  the  mandibles  move 
sidewise.  Each  maxilla  bears  on  its  outer  end  two  finger- 


90 


MANUAL  OF  GENEEAL  AGEICULTURE. 


like  appendages :  onej  the  galea,  Fig.  13  gl,  is  more  or  less 
spoon-shaped,  the  other 
the  lacinia,  Fig.  13/lc, 
pointed  and  with /two 
teeth.  The  galea  and 
lacinia  aid  in  holding 
the  food  in  the  mouth, 
where  it  can  be  crushed 
by  the  mandibles  and 
masticated.  Each  max- 
illa also  bears  on  one 
side  a  five-segmented 
feeler  or  palpus  (plural 
palpi),  the  maxillary 
palpus.  The  hypophar- 
ynx  is  a  small  tongue- 
like  structure  situated 
in  the  mouth  and  at- 
tached to  the  inner  sur- 
face of  the  lower  lip.  FlG  13._rfc/^.pa;to  of  a  locwt. 
big.  Id  hy.  Ihe  lower  /,  labrum;  md,  mandible;  hy,  hypo- 
lip  or  labium,  Fig.  13  Ib,  pharynx;  mx,  maxilla;  mp,  maxillary 
in  the  locust  and  Other  palpus;  gl,  galea;  Ic,  lacinia;  Ib,  la- 
insects  consists  of  a  ^ium;  lp  labial  palpi;  pgf  paraglos- 

,  .  .,      .  sae;  g,  glossa. 

single     piece;  it    is    in 

reality  a  pair  of  jaws  similar  to  the  maxillae  grown 
together  on  the  middle  line.  The  labium  bears  on  each 
side  a  three-segmented  feeler  or  palpus,  the  labial  palpus, 
Fig.  13  Ip,  and  at  its  apex  two  large,  more  or  less  squan; 
flaps,  the  paraglossae,  Fig.  13  pg,  and  at  the  bottom  of  the 
slit  between  the  paraglossae,  a  minute  projection,  the 
glossa,  Fig.  13  g.  The  glossa  in  the  locust  is  rudimentary, 
but  in  many  biting  insects  it  is  as  long  as  the  paraglossae, 
and,  as  will  be  seen  later,  forms  an  important  part  of  the 
mouth  of  sucking  insects.  Detach  and  draw  the  parts 
shown  in  Fig.  13. 

The  mouth-parts  of  the  locust  illustrate  well  the  form 
and  arrangement  of  the  parts  in  the  mouth  of  biting  in- 


MANUAL  OF  GENEEAL  AGRICULTURE.  91 

sects  in  general.  The  biting  type  is  found  in  cockroaches, 
locusts,  crickets,  beetles,  caterpillars,  and  larvae  of  prac- 
tically all  kinds.  Certain  beetles,  like  the  plum-curculio, 
have  the  front  of  the  head  produced  into  a  long  snout  or 
proboscis  with  the  mouth-parts  at  the  end  of  the  snout. 
The  mouth-parts  of  such  insects  are  like  those  of  the  locust 
and  are  therefore  fitted  for  biting. 

Mouth-parts  Fitted  for  Sucking.  The  mouth-parts  of 
the  locust  have  been  described  in  some  detail  because  the 
mouth-parts  of  sucking  insects  have  all  been  developed  by 
modification  of  the  biting  type.  These  modifications  have 
proceeded  in  different  ways  in  different  groups,  and  are 
so  characteristic  and  peculiar  for  each  group  that  it  is 
possible  for  the  students  of  insects  to  recognize  the  group 
to  which  any  particular  insect  belongs  by  a  study  of  its 
mouth-parts  alone.  Bees  and  wasps  have  one  type ;  the 
two-winged  flies,  as  the  mosquito, 
horse-fly,  and  house-fly,  another ; 
the  true  bugs,  as  the  cicada,  stink- 
bug,  and  squash-bug,  another,  and 
the  moths  and  butterflies  still  an- 
other. 

Bees  and  Wasps.  The  mouth- 
parts  of  these  insects  are  usually 
stated  to  be  of  the  sucking  type ; 
they  are  in  reality  a  combination  B 

of  the  two.  Mandibles,  Fig.  14  md,  PlG.  i*— Honey-bee.  A, 
with  sharp  cuttin  gedges  are  head  of  honey-bee  show- 
usually  present  and  fitted  for  ind  mouth-parts  extend- 
biting,  the  upper  lip  is  small  *d;  B>  maxillae  and  la' 
and  indistinct,  the  maxillae  and  bnm  enlarged' 
labium,  Fig.  14  A,  have  been  greatly  elongated  and 
find  their  greatest  development  in  the  honey-bee 
If  the  maxillae,  Fig.  14  mx,  of  the  honey-bee  are 
compared  with  those  of  the  locust,  it  is  seen  that  the 
lacinia  is  wanting  and  the  maxillary  palpus,  Fig.  14 
mp,  is  reduced  to  a  mere  tubercle.  The  greatest  modi- 
fication is  found  in  the  labium;  the  glossa,  Fig.  14  g,  in 


92        MANUAL  OF  GENEEAL  AGEICULTURE. 

the  locust  a  mere  rudiment,  is  longer  than  any  other  part, 
while  the  paraglossa/e,  large  flaps  in  the  locust,  are  mere 
rudiments  completely  concealed  by 
the  base  of  the  labial  palpi,  which  like 
the  glossa  have  been  greatly  elong- 
ated. The  maxillae  and  labial  palpi 
have  been  hollowed  out  on  one  side, 
and  when  closely  appressed  to  the 
glossa  form  a  tube  for  taking  up  iy 

liquids.     Make  a  drawing  of  the  head 
of  a  bee,  showing  mouth-parts. 

True  Bugs.  The  mouth-parts  of  the  FlG  l5._SquasJl_bug. 
true  bugs  are  so  different  from  those  A,  head  and  thorax 
of  all  other  insects  that  there  cannot  viewed  from  side.  B, 
be  said  to  be  any  resemblance  what-  mouth -parts  sepa- 
soever.  Observe  that  when  the  head  rated  c 
is  examined  from  the  side,  Fig.  15,  a  slender  tube  is  seen 
extending  from  the  apex  of  the  head  along  the  under  side 
of  the  body  between  and  beyond  the  first  pair  of  legs. 
This  tube  is  the  modified  labium,  Fig.  15  Ib.  It  has  a  slit 
en  the  under  side  and  consists  of  three  or  four  segments. 
The  slit  is  triangular  in  outline  near  the  apex  of  the  head; 
it  is  filled  by  a  triangular  shaped  labrum,  Fig.  15  1,  which 
completely  closes  this  part  of  the  tube.  Both  palpi  and 
paraglossae  are  lacking.  Contained  within  this  tube  are 
four  bristle-like  structures;  two  of  them  represent  the 
greatly  modified  mandibles,  Fig.  15  d,  and  two  of  them 
maxillae,  Fig.  15  mx.  They  are  so  changed  in  appearance 
that  their  identity  was  determined  only  by  studying  their 
development.  The  bristle-like  mandibles  and  maxillae 
have  at  their  apices  fine  teeth  with  which  they  can  punc- 
ture the  plant,  and  are  usually  of  about  the  same  length 
as  the  tube ;  but  in  scale  insects,  as  the  San  Jose  scale,  the 
tube  is  very  short  and  the  bristles  are  two  or  three  times 
as  long  as  the  body.  Make  drawing  showing  these  parts. 

Moths  and  Butterflies.  The  mouth-parts  of  a  moth  or 
butterfly  when  not  in  use  are  almost  completely  concealed. 
They  are  rolled  up  into  a  tight  spiral  like  a  watch-spring 


MANUAL  OF  GENERAL  AGRICULTURE. 


93 


A, 


slightly  uncoiled.  B, 
head  with  maxillae 
uncoiled  and  the 
two  maxillae  sepa- 
rated at  apex.  C, 
cross  section  of 
maxillae  to  show  the 
furrow,  f,  formed 
~by  their  appres- 
sion. 


on  the  under  side  of  the  head,  Fig. 
16  A.  They  are  not  inconspicuous  be- 
cause of  their  small  size,  for  in  the 
adults  of  many  of  the  larger  Sphinx 
moths  they  are  nearly  six  inches  long, 
but  are  concealed  by  the  flattened 
scales  which  cover  the  body.  The  up- 
per lip  or  labrum  is  reduced  to  a  mere 
rudiment,  the  mandibles  or  biting 
jaws  are  wanting,  the  lower  lip  or  la-  FIG.  16. —  Moth. 
bium  is  represented  by  the  labial  head  with 
palpi,  Fig.  16  Ip,  which  are  rigid  and 
project  up  over  and  in  front  of  the 
face.  The  coiled  tube  consists  of  the 
two  maxillae,  which  have  been  greatly 
elongated  and  closely  appressed  to 
each  other.  Each  maxilla  is  hollowed 
out  or  grooved  on  its  inner  surface, 
Fig.  16  C,  and  by  the  close  apposition 
of  these  grooves  a  tube  is  formed 
through  which  liquid  food  can  be  drawn.  Moths  and  but- 
terflies obtain  their  food  in  great  part  from  the  nectar 
cups  of  flowers.  In  some  moths  the  tips  of  the  maxillae 
are  armed  with  strong  spines,  with  which  they  can  lacer- 
ate the  tissues  of  ripe  fruits  and  set  free  their  juices. 
Make  drawings  of  the  head  of  a  moth  as  shown  in  Fig. 
16  A  andB. 

The  insecticidal  poisons  applied  for  biting  insects 
have  no  effect  therefore  upon  sucking  insects,  because  the 
sucking  insects  puncture  the  plant  tissue  and  feed  upon 
the  juices  of  the  plant  beneath  the  poisonous  coating  on 
the  surface.  Since  the  poison  cannot  be  taken  up  with 
their  food,  it  is  not  carried  into  their  alimentary  canal, 
and  its  application  produces  no  changes  in  their  life. 

INSECTS  WITH  BITING  MOUTH-PARTS: 
Grasshopper-like  Insects : 

Crickets,  katydids,  meadow  grasshoppers,  locusts  or  grasshoppers. 


94  MANUAL  OF  GENEBAL  AGKICULTURE 

Beetles : 

June  bug  or  May  beetle,  Colorado  potato  beetle,  lady  bug,  click 
beetle,  flat-headed  appletree  borer,  firefly,  rosebug,  striped  cu- 
cumber beetle,  cucumber  flea  beetle,  pea  wee-sal,  blister  beetle, 
plum  curculio. 
Larvae : 

Larvae   of  beetles    (grulbs),   larvae    (caterpillars)    of   moths  and 

butterflies,  larvae  of  saw-flies. 
INSECTS  WITH  SUCKING  MOUTH-PARTS: 
True  Bugs: 

Four-lined-leaf-bug,    red-bug,    bed-bug,    chinch-bug,    squash-bug, 
stink-bug,  cicada,  leaf  hopper,  aphids  or  plant  lice,  pear-tree 
psylla,  San  Jose  scale. 
Moths  and  Butterflies: 

Codling  moth,  bud-moth,  clothes-moth  (larvae  have  biting  mouth- 
parts),  peach  tree  borer  moth  (larvae  have  biting  mouth- 
parts),  canker-worm  moth,  measuring- worm  moth,  cut-worm 
moth,  tomato-worm  moth,  Cecropia  moth,  Polyphemus  moth, 
Luna  moth,  tent  caterpillar  moth,  Cabbage  butterfly,  Monarch 
butterfly,  Viceroy  butterfly,  Red  Admiral  butterfly.  Mourning 
Cloak  butterfly. 
Adults  of  two-winged  flies: 

Mosquito,  black  fly,  horse  fly,  syrphus  fly,  bot  fly,  house  fly,  horn 

fly,  blow  fly. 
Bees  and  Wasps: 

Yellow  jacket,  hornet,  carpenter  bee,  bumble  bee,  leaf  cutter  bee, 
honey  bee. 

Of  the  insecticides  chief  among  the  poisons  are  Paris 
Green  and  arsenate  of  lead.  Among  the  contact  remedies 
lime,  sulphur  and  tobacco.  Obtain  without  cost  the  third 
reference  "Destructive  Insects  and  Their  Control"  and 
experiment  with  one  each  of  the  two  classes  of  insects 
found  destructive  to  vegetation  in  your  region.  Every 
experiment  station  publishes  literature  on  the  control  of 
insects  within  its  State  so  that  it  is  possible  to  obtain  defi- 
nite information  about  almost  any  destructive  insect. 

PART  VI.     TESTING  MILK  AND  ITS  PRODUCT. 

70.     EXPERIMENTS  WITH  MILK. 
Materials:     Milk,  microscope,  litmus  paper,  rennet, 
two  evaporating  dishes,  dilute  acetic  acid. 

(a)  Examine  a  drop  of    milk    with    a    microscope. 
Make  a  drawing. 

(b)  Test  the  reaction  of  milk  with  litmus  paper. 


MANUAL  OF  GENEEAL  AGRICULTUEE.  95 

(c)  (1)     Warm  some  milk  in  a  test  tube  to  a  tem- 
perature of  the  body   (98°  F.)   and  add  a  few  drops  of 
rennet.    A  curd  of  casein  is  soon  formed. 

2.  Kepeat  (1),  but  boil  the  rennet  first.  What  effect 
does  boiling  have  on  the  rennet  or  enzyme? 

(d)  Place  20  c.c.  water  in  an  evaporating  dish  and 
20  c.c.  milk    in    another    evaporating    dish.     Heat    both 
equally  near  the  fire  to  boiling.    Which  boils  first  ?    What 
does  this  show  about  the  boiling  point  of  milk  compared 
to  that  of  water?    Notice  the  scum  which  formed  on  the 
boiled  milk.   Remove  it  and  heat  the  milk  again.    Result? 
What  is  the  nature  of  this  scum?     The  formation  of  this 
scum  is  not  a  true  coagulation. 

(e)  To  about  10  c.c.  milk    add  one  drop  of   dilute 
acetic  acid  and  boil.    The  casein  is  coagulated  and  brings 
down  with  it  the  fat.    This  is  a  true  coagulation. 

71.     ANALYSIS  OF  MILK. 

Materials :  Milk,  2  beakers,  cylinder  or  large  beaker, 
watch  crystal,  water  bath,  acetic  acid,  filter,  filter  paper, 
alcohol,  stirring  rod,  ether,  crucible,  scales. 

(a)  1.  Weigh  a  small  beaker,  place  50  c.c.  of  milk 
in  it  and  weigh  again.  Subtract  and  the  difference  in 
weight  equals  the  weight  of  milk  taken.  Record  this 
weight. 

Pour  the  50  c.c.  of  milk  into  a  large  beaker  or  cylin- 
der and  add  100  c.c.  of  distilled  water.  Rinse  out  the 
small  beaker  with  100  c.c.  more  of  distilled  water  and 
add  to  the  beaker  or  cylinder.  Be  sure  the  small  beaker 
is  well  rinsed.  Mix  well  and  while  stirring  gently,  add 
dilute  acetic  acid  (1-10)  drop  by  drop,  until  the  precipi- 
tate stops  forming.  Test  this  by  transferring  a  drop  of 
the  liquid  to  a  watch  crystal,  adding  a  drop  of  acetic 
acid.  If  no  precipitate  forms,  the  solution  is  ready  to  set 
aside  over  night.  This  precipitate  contains  casein  and 
fat.  Milk  sugar  and  albumen  are  in  the  water  solution. 

2.  Filter  and  remove  all  the  casein  after  it  has  set 
over  night  and  save  filtrate.  Drain  carefully,  squeeze  out 
water  from  the  filter  paper  into  filtrate.  Transfer  this, 


96  MANUAL  OF  GENEKAL  AGBICULTUB^. 

wet  precipitate  to  a  small  dry  beaker  and  add  30  c.c.  of 
alcohol  and  stir.  Filter  a  second  time  and  squeeze  filter 
paper  as  dry  as  possible.  Transfer  the  precipitate  to  an- 
other small  beaker  ai(id  add  50  c.c.  ether.  Heat  on  a 
water  bath  a  little  warmer  than  milk  warm,  ten  minutes, 
stirring  constantly.  Filter  and  save  both  precipitate  and 
nitrate.  The  precipitate  is  the  casein.  Spread  open  the 
paper  in  order  for  the  ether  to  evaporate  and  allow  it  to 
dry.  Place  the  dried  casein  in  a  weighed  dish  and  weigh. 
The  difference  in  weights  equals  the  weight  of  casein. 

To  get  the  per  cent  of  casein  in  the  milk,  divide  the 
weight  of  the  casein  multiplied  by  100  by  the  weight  of 
milk  taken  in  the  beginning,  thus: 

grams  casein       1AA_  .      .         ... 

-   x  100=%  casein  in  milk, 
grams  milk 

The  nitrate   contains  the   fat  dissolved  in  ether.    Evap- 
orate the  ether  by  placing  the  beaker  over  a  heated  water 
bath  and  the  fat  will  be  left.    Weigh  and  the  difference 
between  weight  of  beaker  plus  fat  and  weight  of  beaker, 
equals  the  weight  of  fat.     Get  per  cent  of  fat  in  milk 
by  dividing  the  weight  of  fat  multiplied  by  100  by  the 
weight  of  milk  taken  in  the  beginning,  thus: 
grams  fat      z  100e=%  fat 
grams  milk 

The  ether  dissolved  the  fat  out  of  the  casein.  Casein 
is  not  soluble  in  ether. 

Go  back  to  the  first  filtrate  (after  you  filtered  off  the 
acetic  acid  from  the  casein.)  Throw  away  half  the  solu- 
tion or  save  for  a  second  trial  and  evaporate  the  other 
half  over  a  flame.  This  contains  the  water,  milk  sugar, 
lactic  acid,  and  albumen.  As  you  heat  the  solution,  note 
the  coagulation  of  the  albumen.  When  the  albumen  has 
coagulated,  filter.  Evaporate  the  filtrate  to  dryness,  but 
do  not  burn  it.  Sugar  will  be  left.  Test  with  Fehling's 
solution.  (See  Exercise  37,  a.)  Does  the  milk  sugar  crys- 
talize  readily? 

(b)  To  find  per  cent  of  solids  and  ash  in  milk. 
Weigh  5  c.c.  milk  in  an  evaporating  dish.  Evaporate  it 
over  the  flame  carefully,  taking  care  not  to  blacken  it,  as 


MANUAL  OF  GENERAL  AGRICULTURE.        07 

some  carbon  would  be  consiimed  as  carbon  dioxid.  Fin- 
ish evaporating  in  a  water  bath,  then  heat  in  an  oven  at 
100°  C.  or  212°  F.  for  fifteen  minutes.  Cool  and  weigh. 
Place  again  in  the  oven  for  fifteen  minutes.  Cool  and 
weigh,  and  if  the  two  weights  are  the  same,  get  per  cent  by 
dividing  the  weight  of  the  milk  after  water  is  evaporated 
out  by  the  weight  of  the  milk  taken.  The  result  will  be 
the  per  cent  of  total  solids  in  the  milk.  What  is  the  per 
cent  of  water?  Transfer  to  a  clean  crucible  and  place 
over  a  flame  and  burn  off  the  organic  material.  Burn 
until  the  ash  is  perfectly  white.  Cool  and  weigh.  Divide 
the  weight  of  the  ash  by  the  weight  of  milk  taken  and  the 
result  is  the  per  cent  of  ash  in  the  milk.  This  ash  con- 
tains the  mineral  salts.  Save  for  the  next  experiment. 

72.  TESTS  FOR  THE  MINERAL  SALTS  IN  THE  ASH 
OF  MILK. 

Sodium  and  Potassium.  Treat  1-3  the  ash  of  milk  ob- 
tained in  the  previous  experiment  with  10  c.c.  distilled 
water.  Filter  and  test  1-3  the  filtrate  with  litmus  to  see 
if  it  is  neutral.  Dip  a  platinum  wire  in  this  1-3  and  test 
for  potassium  and  sodium  in  the  flame.  Use  purple  glass 
for  potassium  as  in  the  presence  of  sodium,  potassium  can- 
not be  seen. 

Chlorids.  Test  the  second  portion  of  the  distilled 
water  solution  for  chlorids  by  acidifying  with  a  few  drops 
of  nitric  acid,  and  adding  one  drop  of  silver  nitrate  solu- 
tion. A  white  cloudiness  shows  chlorids. 

Iron.  To  the  remainder  of  the  distilled  water  solution 
add  a  few  drops  of  hydrochloric  acid.  Add  a  few  drops 
of  potassium  ferrocyanid.  Let  stand  a  few  minutes.  A 
blue  color  shows  iron. 

Calcium  and  Magnesium.  Take  the  second  portion  of 
ash  and  add  10  c.c.  warm  hydrochloric  acid.  Note  if  any 
gas  is  given  off.  If  so  carbonates  are  present.  To  the 
hydrochloric  acid  solution,  add  ammonium  hydroxid  un- 
til alkalin.  (Test  with  litmus.)  Add  an  equal  amount 
of  ammonium  oxalate  and  heat  to  boiling.  A  white  pre- 
cipitate shows  the  presence  of  calcium.  Filter  this  and 


98  MANUAL  OF  GENERAL  AGRICULTURE. 

to  the  filtrate  add  a    little    acid    sodium    phosphate.     A 
white  precipitate  shows-magnesium. 

Phosphates.  To^ihe  remainder  of  the  ash  add  nitric 
acid  until  acid  and  add  twice  its  volume  of  ammonium 
molybdate  solution.  Allow  to  stand.  A  fine  yellow  pre- 
cipitate or  color  shows  phosphates.  Place  in  a  table  the 
minerals  found  in  milk. 

73.     CALIBRATION    OR    CORRECTION    OF    GLASS- 
WARE. 

Materials:  Mercury,  scales,  milk,  and  cream  test 
bottles. 

The  correctness  of  the  graduation  of  glassware  may 
be  most  conveniently  and  accurately  tested  by  the  follow- 
ing method : 

(a)  Milk  Test  Bottles.    Weigh  27.10  grams  of  mer- 
cury into  a  perfectly  clean  and  dry  milk  test  bottle.   Since 
the  specific  gravity  of  mercury  is  13.55  or  1  c.c.  weighs 
13.55  grams,  double  this  weight  will  occupy  a  volume  of 
exactly  2  c.c.    Close  the  neck  of  the  milk  test  bottle  with 
a  small,  smooth,  soft  cork,  or  a  wad  of  absorbent  cotton 
cut  off  square  at  one  end.    Press  this  stopper  down  to  the 
first  line  of  the  graduation,  then  invert  the  bottle  so  that 
the  mercury  will  run  into  its  neck.     If    the    total  space 
included  between  0  and  10  marks  is  just  filled  by  the  2 
c.c.  of  mercury,  the  graduation  is  correct. 

The  mercury  may  be  conveniently  transferred  from 
one  test  bottle  to  another  by  means  of  a  thin  rubber  tube 
which  is  slipped  over  the  ends  of  both  bottles  and  one 
weighing  of  mercury  will  thus  suffice  for  a  number  of 
calibrations. 

Mercury  may  be  cleaned  from  mechanical  impurities, 
dust,  water,  etc.,  by  filtration  through  heavy  filter  paper. 
This  is  folded  in  the  usual  way,  placed  in  an  ordinary 
glass  funnel  and  its  point  perforated  with  a  couple  of  pin 
holes.  The  mercury  will  pass  through  in  fine  streams, 
leaving  the  impurities  on  the  filter  paper. 

(b)  Cream  Test  Bottles.    The  cream  test  bottles  may 
be  calibrated  by  the  method  given  for  milk  bottles.    The 


MANUAL  OF  GENEBAL  AGBICULTURE.  99 

neck  of  a  cream  bottle  that  measures  fifty  per  cent  fat  will 
hold  10  c.c.  or  135.5  grams  of  mercury. 

(c)  Pipette  and  Acid  Cylinder.  In  calibrating  the 
pipette  sufficiently  accurate  results  may  be  obtained  by 
weighing  the  quantity  of  water  which  the  pipette  will  de- 
liver, viz.,  17.5  grams.  A  measureful  of  water  may  be 
emptied  into  a  small  vessel,  weighed,  and  this  vessel 
weighed  a  second  time.  The  weight  of  the  water  con- 
tained in  the  pipette  is  the  difference. 

Calibration  of  the  acid  cylinder  is  not  necessary  since 
small  variation  in  the  amount  of  acid  measured  out  does 
not  affect  the  accuracy  of  the  test.  In  calibrating  any  of 
the  glassware  water  instead  of  mercury  may  be  used,  but 
is  less  satisfactory  and  not  in  such  general  use. 

74.     DETERMINATION  OF  THE  STRENGTH  OR  SPE- 
CIFIC GRAVITY  OF  SULPHURIC  ACID. 

Materials:  Milk  test  bottle,  scales,  sulphuric  acid  to 
be  used  in  the  Babcock  test,  acid  hydrometer  (See  b.) 

(a)  Weigh  a  dry  test  bottle  and  then  fill  with  acid 
exactly  to  the  zero  mark.  Weigh  again  accurately  and 
the  difference  between  the  two  weights  will  give  the 
weight  of  the  acid.  Empty  the  bottle  and  thoroughly 
rinse  with  water.  Wipe  the  outside  dry.  Fill  with  water 
to  the  zero  mark  as  before  and  weigh.  The  difference  be- 
tween this  weight  and  that  of  the  empty  bottle  gives  the 
weight  of  the  water.  Calculate  the  specific  gravity  by 
dividing  the  weight  of  the  acid  by  the  weight  of  the 
water.  If  the  quotient  is  between  1.82  and  1.83  the  acid 
is  of  correct  strength. 

If  the  acid  is  a  little  too  strong,  later  in  making  tests 
take  less  than  the  required  amount,  perhaps,  about  16  c.c. 
If  too  weak  add  a  litle  more  than  17.5  c.c.  If  the  acid 
is  too  strong  the  better  way  to  do  is  to  pour  the  acid  into 
a  bottle  containing  a  small  quantity  of  water.  Never 
dilute  sulphuric  acid  by  pouring  water  into  the  acid  as 
the  acid  may  be  spattered.  For  more  accurate  results  the 
temperature  of  the  acid  should  be  60°F. 


100  MANUAL  OF  GENEBAL  AGRICULTURE. 

(b)  A  shorter  meikod  is  by  the  use  of  an  acid  hydro- 
meter. When  an  instrument  of  this  kind  is  used  it  is  only 
necessary  to  lower  jt  into  the  acid  and  read  off  the  specific 
gravity. 

75.     THE  BABCOCK  TEST  OF  MILK. 

Materials:  Half  pint  of  milk  (enough  for  entire 
class),  17.6  c.c.  milk  pipettes,  milk  test  bottles,  water- 
white  sulphuric  acid  of  specific  gravity  between  1.82  and 
1.83.  Vessel  for  heating  water,  small  beaker,  dividers, 
(the  latter  desirable  but  not  necessary)  and  Babcock 
tester,  distilled  or  soft  (rain)  water. 

(a)  Sampling  the  Milk.    Be  careful  that  the  sample 
represents  a  fair  average  to  be  tested.     Any  cream  that 
may  rise  on  the  milk  should  be  thoroughly  mixed  with  the 
milk  by  cautiously  pouring  back  and  forth  from  one  vessel 
to  another. 

(b)  Measuring  Milk.    This  is  done  with  a  milk  pipette 
which  holds  when  filled  to  the  mark  on  the  stem,  17.6  cc. 
Suck  the  milk  up  into  the  pipette  above  the  mark  and 
place  the  finger  quickly  on  the  upper  end  of  the  pipette, 
then  press  firmly  down  to  keep  the  milk  from  running 
out.     Hold  the   pipette  vertically  with  the   mark   on  a 
level  with  the  eye  and  by  gently  relaxing  the  pressure  of 
the  finger  on  the  end  of  the  pipette,  air  is  admitted  and 
the  milk  is  allowed  to  flow  slowly  out  until  the  top  of  the 
column  of  the  milk  is  level  with  the  mark  of  the  pipette. 
Read  it  to  the  lowest  part  of  the  curve  or  meniscus.    The 
pipette  then  holds  17.6  cc.  of  milk. 

(c)  Filling  the  Test  Bottles.    Place  the  point  of  the 
pipette  into  the  mouth  of  the  milk  test  bottle,  holding 
both  milk  test  botle  and  pipette  in  an  inclined  position. 
By  removing  the  finger  from  the  end  of  the  pipette  the 
milk  will  flow  out  of  the  pipette  and  into  the  bottle. 

The  object  of  inclining  the  test  bottle  and  pipette  is 
to  allow  the  milk  to  run  down  the  side  of  the  neck  of 
the  test  bottle,  thus  allowing  the  exit  of  the  air  in  the 
bottle.  If  this  precaution  is  not  observed,  the  air  will 
bubble  out  and  cause  some  of  the  milk  to  overflow. 


MANUAL  OF  GENERAL  AGRICULTURE.  101 

Allow  the  pipette  to  drain  into  the  test  bottle  and  blow 
into  the  upper  end  of  it  to  discharge  the  last  drop  of 
milk  in  the  pipette  into  the  test  bottle. 

The  best  results  will  be  obtained  by  having  the 
samples  of  milk  and  also  the  acid  at  the  temperature  of 
60°  F. 

Find  the  ground  or  frosted  part  on  the  body  of  the 
bottle  and  place  on  it  your  initials;  or  better  still  ask 
the  teacher  to  give  you  a  number  corresponding  to  a 
number  by  the  side  of  one  of  the  receptacles  in  the  tester. 
Always  use  the  same  number  and  the  same  bottle  in  order 
to  avoid  confusion. 

(d)  Adding  the  Acid.    After  the  milk  has  been  meas- 
ured into  the  test  bottles,  the  acid  should  be  added.    This 
may  be  done  at  once  or  the  milk  may  be  allowed  to  stand 
in  the  test  bottles  for  a  number  of  days  without  changing 
the  results.     Fill  the  acid  measure  up  to  the  mark   (17.5 
c.c.)  with  sulphuric  acid  of  the  specific  gravity  between 
1.82   and   1.83.      To   pour  the   acid  into   the   test   bottle, 
the  bottle   should  be  placed  in  an  inclined  position   so 
that  the  acid  will  flow  down  the  side  of  the  test  bottle 
and  not  drop  through  the  body  of  the  milk  in  the  bottle. 
By   observing  this   precaution,   charring   of  the   milk   is 
avoided  and  also  spilling  out  of  the  acid.     If  the  acid 
has  been  properly  added,  there  will  be  distinct  layers  of 
acid  and  milk  in  the  test  bottle,  without  any  black  layers 
mixed  between  them. 

(e)  Mixing  the  Milk  and  Acid.    This  is  done  by  giv- 
ing the  test  bottle  a  combined  rotary  and  shaking  mo- 
tion, being  careful  not  to  allow  any  curd  to  get  into  the 
neck  of  the  bottle.     The  shaking  of  the  bottle  should  be 
continued  until  all  the  particles  or  clots  of  curd  are  en- 
tirely dissolved.     The  liquid  will  then  be  a  dark  brown 
color  and  of  a  high  temperature,  due  to  the  chemical  ac- 
tion of  the  acid  on  the  milk.     The  object  of  adding  the 
acid  is  to  dissolve  all  the  solids  in  the  milk,  except  the 
fat  which  is  left  in  suspension  in  the  liquid. 

Caution.  The  acid  is  very  corrosive  and  should  not 
be  allowed  to  get  upon  the  person  or  clothes.  If  any 


102  MANUAL  OF  GENEEAL  AGEICULTURI1. 

should  be  spilled  on-^the^skin  or  clothing,  it  should  be 
quickly  washed  off  with  water.  Color  can  be  restored 
to  clothing  by  treating  the  spot  at  once  with  ammonia 
water. 

(f)  Whirling  the  Bottles.    Place  the  test  bottles  with 
the  milk  and  acid  properly  mixed  in  the  tester  or  centri- 
fugal machine.     The  bottles  should  be  arranged  in  pairs 
at  the  opposite  side  of  the  center,  so  that  they  will  balance 
when  rotating.    It  is  better  to  put  the  bottles  into  a  tester 
directly  after  mixing  the  milk  and  acid,  while  the  bottles 
are  hot.     If,  however,  this  should  not  be  convenient,  the 
bottles  may  be  allowed  to  stand  an  indefinite  period,  but 
when  they  are  placed  in  the  machine,  means  should  be 
provided  for  heating  them  while  rotating  so  as  to  keep 
the  fat  in  a  melted  condition.     This  is  done  in  the  steam 
machine  by  turning  on  a  steam  jet  provided  for  that  pur- 
pose or  in  the  hand  machine  by  placing  boiling  water  in 
the  bottom  of  the  tester  and  putting  on  the  cover  at  once 
to  retain  the  steam.     The  bottles  should  be  whirled  for 
five  minutes  at  the  speed  marked  on  the  machine,  and 
then  the  machine  allowed  to  slowly  come  to  rest  for  the 
purpose  of  adding  hot  water. 

(g)  Adding  Hot  Water.     The  object  of  adding  hot 
water  is  to  bring  the  fat  up  into  the  graduated  portion 
of  the  neck  where  it  can  be  measured.    Boiling  hot  water 
should  be  added  by  means  of  the  pipette  or  a  beaker. 
Perfectly  clear  readings  can  be  insured  by  adding  the 
water  in  two  installments.    First,  add  enough  hot  water 
to  bring  the  fat  to,  but  not  into,  the  neck  of  the  bottle, 
then  whirl  for  two  minutes.     Stop,  and  add  enough  hot 
water  to  bring  the  fat  into  the  graduated  part  of  the 
neck,  adding  the  water  gradually  so  as  not  to  overflow 
the  fat.     Whirl  a  third  time  for  one  minute.     With  this 
method  a  beautifully  clear  reading  should  result  with  a 
layer  of  clear  water  below  the  fat.     If  the  reading  of  the 
fat  is  at  all  cloudy  add  a  little  hot  water  and  whirl  again. 
It  is  desirable  to  use  distilled  water,  rain  water,  or  soft 
water  of  any  kind. 


MANUAL  OF  GENERAL  AGRICULTURE.  103 

(h)  Reading  the  Test.  The  fat,  if  the  bottles  have 
"been  kept  at  a  proper  temperature,  will  be  liquid  and  will 
be  level  or  right  angled  to  the  neck  of  the  bottle  at  the 
ends  of  the  fat  column.  To  read  the  per  cent  fat,  hold 
the  bottle  up  with  the  fat  on  the  level  with  the  eye  and 
read  the  graduations  at  each  end  of  the  column  of  fat. 
Make  a  liberal  reading  by  including  the  upper  and  lower 
meniscus  in  the  reading.  Each  small  division  represents 
two  tenths  of  one  per  cent  of  fat  and  the  large  spaces 
numbered  1,  2,  3,  etc.,  to  10,  represent  one  per  cent  of 
fat  each.,  By  subtracting  the  readings  taken,  the  per- 
centage of  fat  is  obtained.  Thus  if  the  top  of  the  fat 
column  is  at  7.4  and  the  bottom  at  2.6  the  reading  is  7.4 
less  2.6  equals  4.8  per  cent  fat,  which  means  that  in  100 
Ibs.  of  milk  there  are  4.8  Ibs.  of  fat.  The  reading  may  be 
more  easily  done  by  using  a  pair  of  dividers. 

(i)  Washing  the  Test  Bottles.  This  is  done  most 
easily  if  the  bottles  are  emptied  at  once  after  making  the 
test  and  while  hot.  They  should  be  given  a  rotary  mo- 
tion which  allows  the  air  to  enter  and  empties  them 
quicker,  besides  carrying  off  the  sediment  that  is  on  the 
bottom  of  the  bottles.  Einse  thoroughly  with  boiling 
water  to  remove  the  grease,  dirt,  and  acid  solution  from 
the  inside.  Occasionally  boil  the  bottles  in  water  con- 
taining a  little  cleaning  powder. 

76.     THE  BABCOCK  TEST  OF  CREAM. 

Materials:  Babcock  tester  and  accompanying  ap- 
paratus, cream,  two  fifty  per  cent  test  bottles. 

In  testing  cream  inaccurate  results  will  be  obtained 
if  17.6  c.c.  cream  is  measured  out  in  a  pipette  as  in  the 
case  of  milk.  In  the  first  place  the  specific  gravity  of 
cream  is  lower  than  that  of  milk.  The  specific  gravity  of 
20%  cream  will  be  considerably  more  than  40%  cream. 
Also  cream  will  adhere  more  to  the  sides  of  the  pipette 
than  milk.  Hence  accurate  tests  of  cream  can  only  be 
made  by  weighing  the  cream  in  the  Babcock  test  bottle. 

Place  a  cream  test  bottle  on  each  side  of  the  scales 
and  see  that  they  are  accurately  balanced.  Place  18 


104  MANUAL  OF  GENEEAL  AGEICULTUEEI. 

grams  in  weights/on-one  side.  Take  the  sample  of  cream 
to  be  tested  and  warm  it  by  shaking  the  cream  and  vessel 
in  a  pail  of  water  as  hot  as  the  hand  will  bear  for  one  or 
two  minutes.  (The  cream  should  not  rise  above  90°  F). 
Mix  by  pouring  from  one  bottle  to  another  four  or  five 
times.  Suck  up  the  cream  into  the  milk  pipette  until 
the  upper  level  is  an  inch  or  so  above  the  17.6  c.c.  mark. 
Gradually  let  it  run  into  one  of  the  bottles  until  the 
scales  just  balance.  Remove  the  weights,  leave  both 
bottles  on,  and  in  a  similar  manner  pour  cream  from  the 
same  sample,  or  another  sample  to  be  tested,  into  the 
empty  bottle  on  the  other  side  until  the  scales  just 
balance.  Add  the  acid  and  complete  the  test  the  same  as 
for  milk. 

Unless  the  reading  is  done  quickly  the  bottles  should 
be  placed  in  water  from  140°  to  150°  F.,  the  water  rising 
nearly  to  the  top  of  the  necks.  Let  them  remain  there 
five  minutes,  then  perfectly  clear  readings  can  be  ob- 
tained. This  is  necessary  when  several  samples  are  to 
be  tested  by  one  operater,  as  the  fat  will  contract  from 
the  cold  and  slip  down  the  neck  before  all  can  be  read. 

77.     THE  BABCOCK  TEST  OF  SKIM  MILK. 

Materials:  Skim  milk  bottle,  17.6  cc.  pipette,  acid 
cylinder,  sulphuric  acid,  half  pint  of  separator  skim  milk. 

The  Babcock  test  of  skim  milk,  butter  milk,  and 
whey  is^the  same  as  that  of  milk  except  as  indicated  in 
this  experiment. 

A  double  necked  test  bottle  is  made  especially  for 
measuring  small  amounts  of  fat.  The  smaller  neck  will 
measure  .25  of  one  per  cent,  each  of  the  smaller  gradua- 
tions representing  .01  of  one  per  cent. 

To  make  a  test  measure  out  17.6  c.c.  of  skim  milk 
with  a  pipette  as  was  done  with  milk  and  then  pour  it 
into  the  larger  neck  of  the  skim  milk  bottle.  Next  slowly 
add  the  sulphuric  acid,  but  instead  of  using  17.5  c.c.  of 
acid  use  20  c.c.  Place  in  the  tester  with  the  filling  tube 
toward  the  center.  Whirl  and  add  water  in  the  usual 
manner,  but  it  is  highly  desirable  to  use  either  distilled  or 


MANUAL  OF  GENERAL  AGRICULTURE.  105 

rain  water.  Make  a  liberal  reading  as  in  the  case  of  milk. 
Some  difficulty  may  be  encountered  in  getting  the  smaller 
amount  of  fat  within  the  scale.  This  may  be  overcome 
by  putting  a  cork  into  the  neck  of  the  large  opening  and 
gently  working  it  up  and  down  so  that  it  will  be  possible 
to  regulate  the  position  of  the  fat.  Make  a  reading  as 
quickly  as  possible  or  the  fat  may  adhere  to  the  inside  of 
the  neck  as  a  film  of  grease  which  cannot  be  measured  by 
the  scale.  A  test  of  .02  of  one  per  cent  shows  an  efficient 
separation. 

A  test  of  skim  milk  showing  no  fat  in  the  neck  of  the 
test  bottle  on  completion  of  the  test  generally  shows  poor 
work  on  the  part  of  the  operator  and  should  be  repeated. 

Obtain  some  butter  milk  and  also  some  whey  and 
test  each  the  same  as  skim  milk  except  that  in  the  case 
of  whey  17.5  c.c.  of  acid  is  sufficient  since  whey  contains 
less  solids  not  fat  for  the  acid  to  dissolve. 

78.     THE  LACTOMETER  AND  ITS  APPLICATION. 

Materials:  Quevenne  lactometer,  500  c.c.  cylinder, 
pint  of  milk,  pint  of  skim  milk. 

The  specific  gravity  of  normal  cow's  milk  will  vary 
in  different  samples  between  1.029  and  1.035  at  60  degrees 
F.,  the  average  being  about  1.032.  The  lactometer  is 
used  for  determining  the  specific  gravity  of  milk.  There 
are  two  in  use :  the  Quevenne  and  the  Board  of  Health. 
Only  the  Quevenne  will  be  considered. 

The  Quevenne  lactometer  consists  of  a  hollow  cylinder 
weighted  by  means  of  mercury  so  that  it  will  float  in 
milk  in  an  upright  position,  and  provided  with  a  narrow 
stem  at  its  upper  end,  inside  of  which  is  found  a  grad- 
uated paper  scale.  A  thermometer  is  placed  in  the  cylinder 
with  its  bulb  at  the  lower  end  of  the  lactometer  and  its 
stem  rising  above  the  lactometer  scale.  The  scale  is 
marked  at  15  and  40,  and  divided  into  25  equal  parts, 
with  figures  at  each  five  divisions  of  the  scale.  The  single 
divisions  are  called  degrees.  The  fifteen  degree  mark 
is  placed  at  the  point  to  which  the  lactometer  will  sink 
when  lowered  into  a  liquid  of  a  specific  gravity  of  1.015 


106  MANUAL  OF  GENERAL  AGRICULTURE. 

and  the  40  degree  mark  at  the  point  to  which  it  will  sink 
when  placed  in  a  liquid  of  a  specific  gravity  of  1.040. 
To  mix  thoroughly  pour  the  sample  to  be  tested  from  one 
receptacle  to  another  then  fill  a  250  c.c.  or  larger  cylinder 
about  three  fourths  full.  Carefully  lower  the  lactometer 
into  the  cylinder  until  it  floats.  In  about  half  a  minute 
take  the  lactometer  reading  and  the  temperature  read- 
ing. In  reading  the  lactometer  degrees  the  mark  on 
the  scale  plainly  visible  through  the  upper  portion  of 
the  meniscus  should  be  noted.  When  the  lactometer  de- 
gree is  known,  the  corresponding  specific  gravity  is  found 
by  dividing  by  1000  and  adding  one  to  the  quotent. 

Example:  If  the  lactometer  reading  is  34.3  and  the 
temperature  60°,  the  specific  gravity  is  34.3-=-1000=.0343 ; 
.0343  plus  1—1.0343. 

Like  most  liquids  milk  will  expand  on  being  warmed, 
and  the  same  volume  will  weigh  less  when  warm  than 
before ;  i.  e.,  its  specific  gravity  will  be  decreased.  There- 
fore the  lactometer  is  standardized  to  60°.  It  is  incon- 
venient to  always  have  milk  at  exactly  this  temperature. 
By  making  a  temperature  correction  milk  between  50° 
and  70°  may  be  tested,  but  outside  of  a  range  of  10°  on 
either  side  of  60°  the  test  will  be  inaccurate.  To  make 
the  temperature  correction  add  .1  to  the  lactometer  read- 
ing for  each  degree  above  60°F.,  and  subtract  .1  for  each 
degree  below  60°;  e.g.,  if  the  reading  at  63°  is  33.6  it  will 
be  33.6  plus  .3=33.9  at  60°.  The  specific  gravity  would 
then  be  33.9  divided  by  1000=.0339.  .0339  plus 
1=1.0339.  If  the  reading  is  30  at  54°  the  corrected 
reading  will  be  30— .6=29.4. 

Test  the  specific  gravity  of  a  sample  of  skim  milk 
and  of  a  sample  of  milk  with  a  small  amount  of  water 
added. 

Question:  1.  Under  what  conditions  would  it  be 
difficult  to  detect  adulteration  with  water? 

2.  When  could  the  presence  of  water  be  easily  de- 
tected? 


MANUAL  OF  GENEKAL  AGEICULTUEE.  107 

79.  TESTING  THE  ACIDITY  OR  SOURNESS  OF 

MILK  AND  CREAM. 

Materials:  Samples  of  milk  and  cream,  50  c.c.  bu- 
rette* provided  with  stopcock,  17.6  c.c.  pipette,  a  tin, 
porcelain  or  glass  cup,  %  gallon  neutralizer,  indicator. 

With  a  17.6  c.c.  pipette  measure  into  a  clean  cup  this 
amount  of  milk  and  add  a  few  drops  of  indicator.  Attach 
the  burette  to  a  ring  stand  and  fill  with  the  alkali  solu- 
tion nearly  to  zero  mark.  Eead  accurately  the  top  of 
the  column.  Next  cautiously  add  the  neutralizer  from 
the  burette.  By  constant  stirring  during  the  operation 
it  will  be  noticed  that  the  pink  color  formed  by  the  addi- 
tion of  even  a  drop  of  alkali  will  at  first  entirely  dis- 
appear, but  as  more  and  more  of  the  acid  in  the  sample 
becomes  neutralized,  the  color  will  disappear  more  slowly, 
until  finally  a  point  is  reached  when  the  pink  color  re- 
mains permanent  for  a  time.  No  more  alkali  should  be 
added  after  the  first  appearance  of  a  uniform  pink  color 
in  the  sample.  Take  a  second  reading  of  the  column. 
Ascertain  the  amount  of  alkali  solution  used  by  subtract- 
ing the  readings  of  the  scale  on  the  burette.  The  per 
cent  of  acidity  may  be  obtained  by  dividing  the  number 
of  c.c.  used  by  20.  The  result  will  be  the  per  cent  of 
acidity  in  tenths.  For  example  if  17.6  c.c.  of  milk  re- 
quired 3  c.c.  of  alkali  solution  to  give  a  pink  color  the 
per  cent  of  acid  is  8-^20= .4%. 

80.  CALCULATION  OF  THE  PERCENTAGE  OF 

MILK  SOLIDS. 

Materials :  One  or  two  pint  samples  of  milk,  cylinder, 
lacometer,  Babcock  tester  and  accompanying  materials. 

The  calculation  of  milk  solids  can  be  easily  done  by 
using  the  following  formulas : 

Per  cent  of  Solids  not  fat=%L+.2f. 

Per  cent  of  Total  Solids=H4L+1.2f. 

*In  the  Marshall  Acid  Test  the  per  cent  acidity  can  be  read 
directly.  If  no  burette  is  at  hand  the  outfit  for  this  test  had 
better  be  purchased. 


108  MANUlr-eiMENERAL  AGEICULTURE. 


L  being  the  lactometer  reading  at  60°F  or  corrected 
for  temperature,  and  f  the  per  cent  of  fat  in  the  milk. 

Example.  If  the  lactometer  reading  (L)  is  31.2, 
the  temperature  (T)  is  64°  and  the  per  cent  of  fat  (f) 
is  3.6  the  calculation  of  Solids  not  fat  is  as  follows: 
31.2+.4=31.6,  the  corrected  lactometer  reading,  adding 
.1  for  every  degree  over  60°. 

Per  cent  of  solids  not  fat=:V4L+.2f, 

=%x31.6+.2x3.6 
=7.9+.  72=8.62% 
Per  cent  total  solids        =%L+1.2f, 

=7.9+4.32=12.22% 

Or  for  per  cent  of  total  solids  simply  add  the  fat 
to  the  solids  not  fat  as  8.62+3.6=12.22. 

81.     TEST  FOR  PHYSICAL  ADULTERATION 
OF  MILK. 

Materials:  Lacometer,  Babcock  tester,  normal, 
watered,  skimmed,  and  watered-and-skimmed  milk. 

Milk  may  be  adulterated  by  being  watered,  skimmed, 
or  both  watered  and  skimmed. 

If  the  analysis  of  the  suspected  sample  shows 
sp.  gr.  of  milk  .......................................  )  JQW  } 

fat  and  solids  not  fat  .......  .  .......  -  f  [•  watered 

sp.  gr.  of  solids  .......................  ™  ......  normal  ) 

sp.  gr.  of  milk  and  of  solids....  j.    .  ) 

solids   not   fat  .................  .....................  f  hl£h  V  skimmed 

fat  and,  solids  .............  ..  ........................  low  ) 

sp.  gr.  of  milk  .......................................  normal  }  watered 

sp.   gr.  of  solids  .................................  normal  or  high  >       and 

fat  and  solids  not  fat  ..................  low  )  skimmed 

Latitude  of  variation. 

Specific  gravity  of  milk  may  vary  from  1.029  to  1.035. 
Fat  must  not  fall  below  3. 

Solids  not  fat  must  not  fall  below  9.  (in  most  states.) 
Specific  gravity  of  solids  may  vary  between  1.25  and 
1.34. 


MANUAL  OF  GENERAL  AGEICULTUEE.  109 

The  specific  gravity  of  (milk)  solids  is  determined  by 

t 
the  following  formula  :     S== — 

100s— 100 
t 


s 

S  being  the  specific  gravity  of  the  milk  solids,  s  that  of 
the  milk  and  t  the  total  solids  of  the  milk. 

Example:  A  sample  of  milk  has  been  found  to  con- 
tain 13.  per  cent  of  total  solids,  sp.  gr.  1.032 ;  then 
100s— 100  100x1.032—100 

—=3.101;   t— this  or   13.— 3.101 
s  1.032 

13. 
=9.899;  then  dividing  t  by  this,  -  —=1.31,  the  specific 

9.899 

gravity  of  milk  solids.  Let  the  teacher  furnish  samples 
of  normal,  watered,  skimmed  and  watered-and-skimmed 
milk  and  the  class  determine  each. 

82.  TEST  FOR  CHEMICAL  ADULTERATION  OF 
MILK. 

Materials:  Salicylic  acid,  formalin  in  samples  of 
milk,  ether,  surphuric  acid,  alcohol,  iron  chlorid  solution, 
hydrochloric  acid,  evaporating  dish. 

(a)  Salicylic  Acid.     To  20  c.c.  of  milk  add  from  2 
to  3  c.c.  sulphuric  acid  and  4  to  5  c.c.  ether  and  stir  in 
an  evaporating  dish.     Evaporate  and  treat  the  residue 
with  about  3  c.c.  alcohol,  add  a  few  drops  of  iron  chlorid 
solution  and  heat  again.    A  deep  violet  color  will  be  ob- 
tained in  the  presence  of  salicylic  acid. 

(b)  Formalin  (Formaldehyde).     To  one-fourth  test 
tube  of  milk  add  an  equal  volume  of  water  and  5  to  10 
c.c.  sulphuric  acid  used  in  testing.    A  violet  ring  is  formed 
at  the  junction  of  the  two  liquids  if  formalin  is  present ; 
if  not,  a  slight  greenish  tinge  will  be  seen.    The  violet 
color  is  not  obtained  with  milk  containing  over  .05  per 
cent  formalin. 


110  MANUALuXIE^GENERAL  AGRICULTURE. 

(c)     Formalin  (optional). 

To  10  c.c.  of  milk  in  an  evaporating  dish  add  an  equal 
volume  of  hydrochloric  acid.  Add  one  drop  of  ferric 
chlorid  solution,  heat  gently,  stirring  until  contents  are 
nearly  boiling.  The  formaldehyde  turns  the  casein  of  the 
milk  violet.  If  no  formalin  is  present  the  liquid  turns 
brown  only. 

83.     DETERMINATION  OF  MOISTURE  IN  BUTTER. 

Materials :  300  c.c.  aluminum  cup,  butter  to  be  tested, 
ring  stand,  spatula  or  spoon,  fine  wire  or  thread,  scales, 
alcohol  lamp. 

Anyone  who  is  familiar  with  testing  of  butter  for 
moisture  is  well  aware  of  the  fact  that  an  accurate  test  is 
not  possible  unless  the  sample  taken  for  testing  is  a  repre- 
sentative one.  In  view  of  the  heavy  penalties  imposed  be- 
cause of  excessive  moisture,  no  buttermaker  can  afford  to 
do  the  work  ignorantly  or  carelessly.  The  matter  of 
proper  ways  of  taking  samples  and  of  testing  is  as  yet 
more  or  less  unsettled,  but  the  following  suggestions  are 
generally  recognized  as  being  worthy  of  attention. 

In  taking  a  sample  from  the  churn,  remove  a  portion 
of  the  surface  of  the  butter  at  vairous  places  of  the  churn, 
and  by  means  of  a  spatula  or  spoon  take  out  small  pieces. 
Butter  in  the  churn  contains  many  water  pockets  and 
these  must  be  avoided,  as  they  are  worked  out  in  packing. 

In  taking  a  sample  from  the  print  use  a  fine  wire  or 
thread  as  butter  can  be  easily  cut  in  this  way.  Several 
small  slices  from  different  parts  of  the  print  are  sufficient. 
As  fast  as  the  slices  are  made,  place  them  in  an  ordinary 
pint  fruit  jar  and  after  they  are  all  in  it,  screw  the  cap 
down  air-tight. 

Samples  taken  as  above  are  approximate  representa- 
tives only,  so  that  in  order  that  the  parts  taken  may  be- 
come a  uniform  mixture,  it  is  necessary  that  they  be 
melted  at  as  low  a  temperature  as  possible  (not  above 
120°  F.)  in  order  that  none  of  the  volatile  substances  pass 
off  as  vapor.  This  may  be  done  by  placing  the  sealed  sam- 
ple in  a  pail  of  water  as  hot  as  the  hand  will  bear  and 


MANUAL  OF  GENEEAL  AGRICULTURE.  Ill 

allowing  it  to  remain  there  a  few  moments,  shaking  occa- 
sionally, until  the  butter  is  melted.  Cool  until  solid,  shak- 
ing often  to  insure  an  even  distribution  of  the  constit- 
uents. 

Special  scales  for  moisture  testing  are  on  the  market, 
but  any  sensitive  scales  will  do. 

See  that  the  scales  are  accurately  balanced.  The 
aluminum  cup  is  capable  of  taking  up  moisture  from  the 
air  and  for  this  reason  must  be  heated  a  moment  or  two 
until  perfectly  dry  and  at  once  accurately  weighed.  When 
the  scales  balance  with  the  beaker  on,  write  down  the 
weight  of  the  beaker  and  then  place  a  10  gram  weight  on 
the  side  opposite  the  beaker. 

Take  the  sample  of  butter,  remove  the  cover,  and 
with  a  spoon  place  butter  in  the  beaker  until  the  scales 
exactly  balance,  giving  a  ten  gram  sample. 

Heat  the  sample  until  all  the  moisture  is  evaporated. 
A  direct  flame  as  that  of  an  alcohol  lamp  is  satisfactory, 
but  care  must  be  taken  not  to  burn  the  butter.  By  shaking 
two  or  three  times  with  a  rotary  motion,  the  burning  of 
the  butter  may  be  prevented. 

After  sputtering  has  ceased,  weigh.  Heat  a  second 
time  and  if  the  weights  are  the  same  upon  reweighing,  all 
the  moisture  has  been  driven  off.  If  the  two  weights  are 
not  the  same,  heat  the  third  time  and  weigh  again  and 
continue  to  reheat  and  reweigh  until  a  constant  weight  is 
obtained. 

Record  results  and  calculate  the  per  cent  of  moisture 
as  follows : 

Weight  of  beaker 38.5  grams 

Weight  of  beaker  and  butter 48.5  grams 

Weight  of  beaker  and  butter  after  heating ...47.     grams 

Weight  of  butter  after  heat 8.5  grams 

Loss  10 — 8.5  1.5  grams 

(1.5-f-10)xlOO=15%  moisture  in  the  sample.  It  is  illegal 
to  sell  butter  containing  more  than  16%  moisture. 


112  MANUAL  OF  GENEKAL  AGKICULTURE. 

84.  DETERMINATION  OF  SALT  IN  BUTTER. 

Materials:  Burette  with  stopcock,  white  cup,  sat- 
urated solution  of  potassium  dichroraate,  silver  nitrate 
solution  made  by  adding  14.531  grams  of  silver  nitrate  to 
1000  c.c.  of  distilled  water.  Butter  to  be  tested,  small  bot- 
tle with  cork  or  cover,  250  c.c.  Florence  flask  with  the 
250  c.c.  height  marked  with  a  file. 

Melt  about  two  ounces  by  guess  of  butter  in  a  small 
covered  bottle  as  was  done  in  testing  for  moisture.  Weigh 
into  the  Florence  flask  exactly  ten  grams  of  the  melted 
sample,  then  add  enough  rain  water  of  a  temperature  of 
about  140°  F.  to  make  250  c.c.  Shake  thoroughly  several 
times  to  dissolve  the  salt.  Take  25  c.c.  (best  obtained 
with  a  25  c.c.  pipette)  of  the  brine  solution  thus  prepared, 
place  it  in  the  cup  and  add  2  or  3  drops  of  potassium 
dichromate  as  an  indicator. 

Place  the  silver  nitrate  solution  in  a  bruette  arranged 
as  in  testing  for  the  acidity  of  milk.  Gradually  let  it  run 
into  the  cup  until  a  permanent  pink  color  remains  upon 
being  thoroughly  stirred.  Note  the  number  of  c.c.  of  sil- 
ver nitrate  used.  Divide  this  number  by  the  factor  2.  The 
result  is  the  per  cent  of  salt  in  the  sample.  As  salt  is  much 
cheaper  than  butter  fat  it  is  to  the  advantage  of  the  butter 
maker  to  add  about  as  much  as  the  market  will  bear. 
Three  per  cent  may  not  be  too  much. 

85.  DETERMINATION  OF  THE  PER  CENT  OF  FAT 
IN  ICE  CREAM. 

Materials:  Glacial  acetic  acid,  sulphuric  acid,  ice 
cream,  Babcock  tester,  and  milk  test  bottle. 

Weigh  nine  grams  of  the  melted  sample  into  a  Bab- 
cock  milk  bottle.  Fill  almost  to  the  neck  with  a  mixture 
of  glacial  acetic  acid  and  sulphuric  acid,  using  equal  vol- 
umes of  each.  Heat  a  few  minutes  until  black,  then  whirl 
in  the  tester  for  five  minutes.  Add  water  to  bring  the  fat 
column  within  the  graduation  of  the  neck  as  in  the  regu- 
lar Babcock  test.  The  reading  multiplied  by  two  gives  the 
per  cent  of  fat  in  the  ice  cream  since  the  bottle  is  gradu- 
ated for  18  grams  and  only  9  grams  were  used. 


MANUAL  OF  GENERAL  AGRICULTURE.  113 

If  sulphuric  acid  alone  is  used  it  is  likely  to  char  the 
sugar  in  the  ice  cream,  thus  giving  difficulty  in  reading 
the  results. 

Ice  cream  should  contain  not  less  than  twelve  per  cent 
of  milk  fat. 

Fruit  ice  cream  and  nut  ice  cream  should  contain  not 
less  than  ten  per  cent  of  milk  fat. 

86.  STANDARDIZATION  OF  MILK  AND  OF  CREAM. 

Materials:  Half  gallon  of  milk  testing  4%  or  over, 
1%  quarts  of  skim  milk,  Babcock  tester  and  accompany- 
ing materials. 

Milk  or  cream  is  " standardized"  or  brought  to  any 
required  test  by  the  addition  of  skim  milk,  milk,  or  cream, 
according  to  the  conditions.  Standardization  is  perhaps 
most  often  a  lowering  of  the  butter  fat  test  to  just  meet 
the  requirements  imposed  by  law. 

The  ordinance  of  the  city  of  Los  Angeles  requires  at 
least  3.5  per  cent  butter  fat.  Probably  most  of  the  milk 
produced  for  Los  Angeles  consumption  will  test  4%  or 
more. 

Example.  Standardize  300  pounds  of  4%  milk  to 
3.5%,  using  skim  milk  testing  .1%. 

300  Ibs.  of  4    •—         ~~    3.4*  300  :   3.4 


Then 


as 


Xlbs.  of  .1    .5  X      :     .5 

Solving,  300:3.4::X:.5 

3.4X=150 

X=44.1 

*The  3.4  and  .5  are  obtained  by  subtracting  diagonally. 

Therefore  to  get  the  standard  of  3.5%  we  must  add 
44.1  Ibs.  of  skim  milk. 
Proof:     300     Ibs.  of     4%  milk=12  Ibs.  of  fat. 

44.1  Ibs.  of     .1%  skim  milk=.Q4  Ibs.  of  fat. 
344.1  Ibs.  of  3.5%  milk=12.04  Ibs.  of  fat. 
Obtain  a  half  gallon  of  milk  testing  4%  or  over  and 
a  half  gallon  of   skim    milk.     Test    each    for   butter  fat. 


114  MANUAL  OF  GENEEAL  AGEICULTUEE. 

Weigh  the  milk.  Calculate  the  number  of  pounds  of  skim 
milk  that  must  be  added  to  bring  the  milk  to  the  standard 
of  3.5%.  (Figure  on  a  test  of  3.6  since  it  is  unsafe  to  risk 
selling  milk  at  exactly  the  standard  as  some  of  the  milk 
delivered  may  fall  below.)  Add  the  calculated  amount  of 
skim  milk,  then  test  the  standardized  milk  to  see  if  it 
tests  3.6. 

REFERENCES  FOR  CLASS  STUDY. 
The  first  books  in  the  list  for  each  part  will  be  found 
more  satisfactory  for  high  school  work. 

Parts   I  and  II 

Fletcher,  S.  W.— Soils. 

Snyder,  H.  S. — Soils  and  Firtilizers. 

King,  F.  F.— The  Soil. 

Roberts,  I.  P.— Fertility  of  the  Land. 

Voorhees,  E.  B. — Fertilizers. 

Hopkins,  C.  G. — Soil  Fertility  and  Permanent  Agri- 
culture. 

Hilgard — Soils. 

The  Soil  Bulletins  of  the  U.  S.  Department  of  Agri- 
culture. 

Bailey,  L.  H. — Cyclopedia  of  American  Agriculture. 

Part  III 

Snyder,  H.  S. — Chemistry  of  Plant  and  Animal  Life. 
Bailey,  E.  H.  S. — Sanitary  and  Applied  Chemistry. 
Snyder,  H.  S. — Chemistry  of  Plants. 
Bulletins  of  the  U.  S.  Department  of  Agriculture. 

Part  IV 

Wickson,  E.  J. — California  Fruits  and  How  to  Grow 
Them. 

Bailey,  L.  H. — Principles  of  Fruit  Growing. 

Warren,  G.  F. — Elements  of  Agriculture. 

Waugh,  F.  A. — Systematic  Pomology. 

Hume,  H.  H.— Citrus  Fruits  and  Their  Culture. 

Lodeman,  E.  G. — Spraying  Plants. 

Osterhout,  W.  J.  V. — Experiments  with  Plants. 


MANUAL  OF  GENERAL  AGRICULTURE.  115 

Bailey,  L.  H. — Pruning  Book,  Horticulturists'  Rule 
Book,  Nursery  Book. 

Bulletins  of  the  U.  S.  D.  A. 

Part  V 

Warren,  G.  F. — Elements  of  Agriculture. 

Bulletin  218,  California  Plant  Diseases,  Agricultural 
Experiment  Station,  Berkeley,  Cal. 

Destructive  Insects  and  Their  Control — Cal.  State 
Board  of  Horticulture,  Sacramento,  Cal. 

Duggar,  B.  M. — Fungous  Diseases  of  Plants. 

Part  VI 

Wing,  A.  H. — Milk  and  Its  Products. 

Farrington  and  Woll — Testing  Milk  and  Its  Products. 

Van  Slyke— Testing  Milk. 

Van  Norman,  H.  E. — First  Lessons  in  Dairying. 

Bulletins  of  the  U.  S.  D.  A. 


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